There are three ways to reset a check engine light.

1. Disconnect the battery, wait approximately 30 minutes, reconnect the battery. This resets the cars computer which also reset the check engine light. On newer OBD (on-board diagnostic) compliant vehicles this usually does not work. See step 2.

2. Reset using an OBD II reader. When you hook an OBD II code reader up to your vehicle, you can reset the computer using the code reader.

3. Fixing the problem. Generally the check engine light comes on for a reason. Usually it is emission related (sensors, gas cap) or electrical (faulty wiring). In this case the way to reset the check engine light is to fix the problem

Another Possible Choice:

At least in my car a 2003 impala to clear the check engine light I pulled a fuse called the PCM fuse from my underhood fuse box overnight and put it back in when I left for work and it cleared. I only do this after getting the code pulled at autozone for free and attempting to fix the problem, in this case it was a EVAP code that I fixed by locating a loose vacuum line. Anyway after a driving cycle which seems to be 90 mi in my car the light will return if the problem is not resolved.

The check engine light comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. A flashing check engine light is an indication of a severe misfire or problem that is likely to harm your engine. Immediate diagnosis and service is needed. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too.

To determine the cause, the vehicle will need to be taken to AutoZone or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area. Or you can buy a handheld computer called a Diagnostic Code Reader that will do the same thing and may be cheaper. Plug the tester into the OBDII port inside the car. You'll find the port under the dash to the right of the steering wheel column. Many auto supply stores will loan you the test unit at no cost or will run the test for you.

Some specific causes for the check engine light to be on are:

• Gas cap left off, not tightened, not installed correctly, or needs to be replaced
• 02 sensor
• Engine misfire - error might clear itself after 3 complete warm-up cycles; not restarts, but warm-ups
• Problem in the emission system, including clogged exhaust or the catalytic converter not functioning properly
• Dirty/clogged air filter
• Dirty MAF sensor
• faulty sensors in exhaust system

There are pages and pages of items that can cause a check engine light to come on. Having it checked with a scan tool will narrow down the problem area.

More comments from Answers.com contributors:

• Not all systems are able to be read by your local auto parts store. For '95 and earlier cars, OBD I is used and can NOT be read by AutoZone or Advanced Auto. A simple paper clip can be used to jump 2 ports on the diagnostic port and have the Engine light flash a certain sequence. This will then tell you the code to refer to for troubleshooting.
• First rule of thumb is to check your gas cap; if it has been screwed on wrong, that will cause your light to turn on. Second, check your engine oil, you might be running low. Next, take it to a mechanic because it could be something worse. It could be anything; broken sensor, engine problems...take it to a mechanic you trust. Or if you still have warranty, take it to the dealer.
• The "check engine light" is by far one of the most misunderstood technological advances by the public. I am sure I will revise this as time goes on as it is an in-depth understanding for the public. It is a warning light that is illuminated when there is a problem with the EMISSION SYSTEM only. Emission system being the pollution control system. Don't get a hard on against it as it is a good thing once you understand it. One point that was brought up a a recent meeting of technicians was that the amount of hydrocarbons is greater when the gas cap is left off than when the engine is running. Hydrocarbons are part of pollution emitted as gasoline evaporates. Going a step farther, one facet of the emission system is the "Evaporative" portion. This is when the fumes from the gasoline are leaking from the system into the outside air. This is one part of the emission system that can trigger a check engine light. I would say that about 7% of the vehicles that have a check engine light are the result of a loose or inadequate gas cap. But understand that many scenarios are possible with the "check engine light" The vehicle's powertrain computer (note that some vehicles have 17 different computers) will run a series of self-tests. They will only run under certain criteria. And they can be vastly different from manufacturer to manufacturer. Some self tests are not run until preceding ones have run successfully. So if there is a problem in one particular area that is preventing another self test from running, you can have a situation where one problem is fixed, but another still exists. If you fix a problem and drive the car through a drive cycle that sets the monitor (or self test) the light will go off as it passes that criteria that triggered it in the first place.

  After 1996, the auto industry went to a idea called OBD II (on board diagnostics). This was to get all the manufacturers onto a similar plane for troubleshooting and powertrain control. While they still differ vastly, many corrections and adaptations were made for technicians to better fix the check engine light problems. Prior to this there were so many different and poor troubleshooting data from a check engine light problem that resolving the problem was much more difficult. Many early warning light of this nature were set to illuminate based on mileage. An Oxygen sensor was one of the things that were meant to be replaced when that mileage was hit. This is much like many current "Change oil lights", that are set based on a preset mileage.

• Check engine lights involve the engine's electronics and/or electrical system, since they are interrelated. My '97 Sable's recent check engine light signified a problem with the camshaft sensor, which had to be replaced. Important, since it works with the ignition system, and while AAA is good to have, I hate being towed. It's a tricky repair, and like most manufacturers, Ford has the system designed to mandate a particular repair tool that's expensive to buy. The job's a pain anyway, and can be tricky, so it's best to have a certified mechanic you trust do it (I do not, repeat, do not, like dealerships for a variety of reasons). Never ignore a check engine light; generally easy to computer diagnose (but prepare to pay for an hour of diagnostics). All dash lights are potentially bogus -- sometimes these things take on a life of their own, signifying nothing, but it's foolhardy to assume that. Hope this helps.

The check engine light (CEL for short) is triggered when one or more of the many sensors on the vehicle detects a not-normalreading,

There are 2 basic steps to determining the cause of the CEL coming on:

1. Have the codes read - many places offer to read the engine codes for free. Autozone even provides a printout of the codes, and a short description of common causes
2. Research those codes! Find out the true cause and reason for the not-normal reading. It is not often that the sensor itself is bad and requires replacing.

   There are countless sources of information on engine DTC (diagnostic trouble codes) on the internet - including WikiAnswers!

Real-life examples:

• DTC code P0402 on 98 Tracer - replaced the EGR valve, light came back. Made my daughter live with it for 2 years. Yesterday I had a few minutes while waiting for the oil to drain and poked around the engine - found a small 2" piece of rubber hose that had softened and collapsed right where the PCV connects. A free piece of hose from Autozone and the light cleared after a few drive cycles!
• Major auto parts chain told me my TSP (Throttle position sensor) was bad due to the CEL being lit up (might have been a P1120 DTC). $40 and 10 minutes to replace - ((_#*&$ light came right back. A few days ago, after doing some reading, I bought a $4 can of throttle body spray cleaner - used 1/2 the can on my 98 Sable - voila! CEL is gone again!

Pay attention to those check engine lights - they're there for a reason. And with the internet today, you can readily find the information to keep your car healthy, and even save some $$ in the process.

(end of editorial rant,... and no more acronyms!)

• Service Engine Soon - SES
• Malfunction Indicator Lamp - MIL

You need to have it scanned,most of smaller repair shops will do it a reasonable price,and give you the trouble code.

Just finding out the code doesn't tell what's wrong, so it may not be worth trying to buy a cheap "code reader". Find a shop you trust and take the vehicle to a professional.

BEWARE - the parts stores are very happy to tell you the DTC code (Diagnostic trouble code), and then encourage you to buy the cited part.

For example, a P0171 or P0174 indicate an oxygen sensor issue - will buying and replacing the O2 sensor FIX the problem? NOT AT ALL LIKELY. Don't just blindly buy the part - been there, done that.

Get the codes read - then research them on the net or talk to a reliable mechanic.

Its the emissions light. On my mercury sable when I get bad gasoline the light tends to go on. Usually if I run the car almost empty and then fill up again it goes out. If not try disconecting the battery.

It could be one, more, or MANY things. That's why it is suggested that you take it to your dealer if it is still under warranty. You can take it to AutoZone and have your "Codes" (what causes the Check Engine Light or "SES" Service engine soon light) read.

It will usually tell you what caused the SES and it should be fairly simple to fix, such as a malfunctioning O2 Sensor.

Some things however can be very complex and it is recommended an AST Certified Mechanic takes a look at the vehicle.

most likely a severe engine misfire. you need to have it checked for codes

Open and read your owner's manual. There you will find the answer to your question. But I will tell you. The computer has detected a fault with the emissions system.

Pull the codes from the computer, match the code to the troubleshooting procedure, follow the procedure to find the source. Repair the source, light will go out if that was the only problem. There are "monitors" or self tests the computer runs the car through a drive cycle, if a problem occurs, it may not run all of the self tests until that problem is taken care. Therefore, another problem may exist. It is emission related. OR hook up a scanner that is capable of clearing codes, and hope that none are still active.

The " check engine light" is by far one of the most misunderstood technological advances by the public. I am sure I will revise this as time goes on, as it is an in-depth understanding for the public. It is a warning light that is illuminated when there is a problem with the EMISSION SYSTEM only. Emission system being the pollution control system. Don't get a hard on against it as it is a good thing once you understand it. One point that was brought up a a recent meeting of technicians was that the amount of hydrocarbons is greater when the gas cap is left off than when the engine is running. Hydrocarbons are part of pollution emitted as gasoline evaporates. Going a step farther, one facet of the emission system is the "Evaporative" portion. This is when the fumes from the gasoline are leaking from the system into the outside air. This is one part of the emission system that can trigger a check engine light. I would say that about 7% of the vehicles that have a check engine light are the result of a loose or inadequate gas cap. But understand that many scenarios are possible with the "check engine light" The vehicle's powertrain computer (note that some vehicles have 17 different computers) will run a series of self-tests. They will only run under certain criteria. And they can be vastly different from manufacturer to manufacturer. Some self-tests are not run until preceding ones have run successfully. So if there is a problem in one particular area that is preventing another self test from running, you can have a situation where one problem is fixed, but another still exists. If you fix a problem and drive the car through a drive cycle that sets the monitor (or self test) the light will go off as it passes that criteria that triggered it in the first place. After 1996, the auto industry went to a idea called OBD II (on board diagnostics). This was to get all the manufacturers onto a similar plane for troubleshooting and powertrain control. While they still differ vastly, many corrections and adaptations were made for technicians to better fix the check engine light problems. Prior to this there were so many different and poor troubleshooting data from a check engine light problem that resolving the problem was much more difficult. Many early warning light of this nature were set to illuminate based on mileage. An Oxygen sensor was one of the things that were meant to be replaced when that mileage was hit. This is much like many current "Change oil lights� that are set based on a pre-set mileage.

Now here is the "why" of a CEL: What is actually turning on the CEL is the Powertrain Control Module(PCM), commonly known as the engine control computer. Inside of a PCM there are actually two separate systems. One is control, the other system is diagnostics. PCM diagnostics acts as "big brother," constantly looking over the shoulder of the control side of the PCM. Diagnostics is constantly monitering systems to see if the expected voltages and values are present. For example: If the PCM diagnostics knows that it has been so many minutes since the engine was first started, then the engine temperature should be around 195 degrees. In our senerio, if the engine is still 160 degrees, it sees a problem, and sets the CEL. The technician has to use pinpoint diagnostics to see if we have a stuck thermostat, if the Engine Coolant Temp(ECT) sensor if sending a false signal, if the wiring between the ECT and the PCM is bad, or if the PCM is faulty and interpreting the signal received from the ECT incorrectly. But the PCM is not capable of monitering everything all at once, so it basically goes down a checklist, over and over again, as you are driving down the road. Sometimes a problem can come and go intermittantly, at the right times so as to avoid detection by the PCM. That is why sometimes a CEL doesn't always come on everytime there is a problem. Sometimes you can unplug a sensor even while the car is running, and it takes a while for the CEL to come on, just because the PCM diagnostics hasen't gotten back around to looking at that area yet.

Our senerio only talked about one area that a PCM moniters. There are dozens of sub-systems that the PCM looks at, and dozens of possible failures within each of those sub-systems, that could cause a CEL.

Most often the cause of this light staying on is a bad EGR valve or a bad O2 sensor.

Y-THINK-Y

A good auto parts store will scan codes for free. However, do you research on other forums to learn what each code could 'really' mean. Most the time it's a vacuum leak. Don't let them sell you expensive sensors before researching the codes.

Problem with emission control system - have vehicle scanned to determine the problem

There are 2 basic steps to determining the cause of the CEL coming on:

1. Have the codes read - many places offer to read the engine codes for free. Autozone even provides a printout of the codes, and a short description of common causes

2. Research those codes! Find out the true cause and reason for the not-normal reading. It is not often that the sensor itself is bad and requires replacing.

There are countless sources of information on engine DTC (diagnostic trouble codes) on the internet - including WikiAnswers!

My real-life examples:

DTC code P0402 on 98 Tracer - replaced the EGR valve, light came back. Made my daughter live with it for 2 years. Yesterday I had a few minutes while waiting for the oil to drain and poked around the engine - found a small 2" piece of rubber hose that had softened and collapsed right where the PCV connects. A free piece of hose from Autozone and the light cleared after a few drive cycles!

Major auto parts chain told me my TSP (Throttle position sensor) was bad due to the CEL being lit up (might have been a P1120 DTC). $40 and 10 minutes to replace - ((_#*&$ light came right back. A few days ago, after doing some reading, I bought a $4 can of throttle body spray cleaner - used 1/2 the can on my 98 Sable - voila! CEL is gone again!

*DTC codes P0171 and P0174 - O2 sensors reported lean fuel conditions on bank 1 & 2 on my 2001 Windstar. Some research later found out the 1999-2003 Windstar 3.8l engines had a known problem and Ford issued a technical service bulletin (TSB) describing exactly how to fix it. Instead of wasting $80 replacing perfectly good 02 sensors, I used that money to buy the parts for the repair.

I have added untold miles to the life of my engine, and kicked up my MPG for real savings!

Pay attention to those check engine lights - they're there for a reason. And with the internet today, you can readily find the information to keep your car healthy, and even save some $$ in the process.

the engine light monitors computer sensors and functions, not vital things like temp. oil pressure etc. when that light is on, there will be a code stored in the computers memory. Most auto supply stores can access and read the codes for you, which will tell you what to look for. your particular vehicle is bad about setting a code for being too lean, probably the intake leaking vacuum

You can either take the vehicle to a shop and have the mechanic connect a code reader to your vehicle

OR

you can take your vehicle to your local auto parts retailer and borrow, rent or buy a code reader that will tell you what's wrong.

Whichever you decide, you won't be able to guess what's wrong, and nobody can help you unless and until you connect the vehicle to a code scanner.

Often it's something relatively simple even though it may be a bit expensive. Oxygen sensors for example can be pricey and you should replace both sides at the same time. On the other hand it can sometimes be as simple as a loose gas cap. The code scanner is a great help and if you intend to do much of your own work it's good to have your own scanner. Scanners can be purchased for as low as $30

GOOD LUCK DRIVE SAFE

mk1505 added 1/6/08

On 1998 and 99 windstars a flashing MIL (check engine light) means that the computer has detected one or more misfiring cylinders. You will need to connect an OBDII compliant scanner to the datalink port under the dash on the drivers side to scan the computers trouble codes and determine which cylinders are misfiring.

Disconnect the NEGITIVE Battery Cable and leve it unplugged for 30 seconds, plug it back up - and it will go out

it means your On Board Diagnostic System has detected a problem. there are hundreds of codes it can tell you, each one means something else. If you have a local autozone, go there and they can tell you what the code you are throwing means.

It could be an engine sensor picking up something wrong, or an oxygen sensor before and after the engine. The transmission is another item, that might have a problem and cause the engine light to pop on.

One user's answer

There are three ways to shut off the "Check Engine Light" discount battery (not recommended): use a scan tool and delete code, or wait 40-80 key cycles, depending what the code was set for.

Now, if you discount the battery for around 5 minutes, the Check Engine Light will come off, BUT all memory will be lost. Therefore, the vehicle would have to "relearn" new criteria/values.

It will come back on as soon as the symptoms are seen again and you won't pass emissions. A scan tool is a decent way (only if vehicle was fixed), BUT when you delete a code, you erase freeze frame data (and, of course, the code itself) making it harder for the next tech to fix the problem.

Finally, the best way is key cycles - AKA warm-up cycles. If the car is properly repaired after 40 (type B misfire) or 80 (type A misfire), if the PCM doesn't see the problem occur, it will automatically erase the code.

Another answer

The easiest and fastest way to reset an engine light on any OBD Toyota (OBD1=95 and older / OBD2=96 and newer), is simply this: Pop your hood, and look for the under-the-hood fuse box. Now look on the fuse cover for a fuse labeled "EFI" and pull that fuse out. Now turn the key to "On," but don't start the engine.

Every computer-controlled Toyota has a memory cell in the computer; by pulling the fuse, you are cutting the power supply to the computer. Turning the key on drains the memory cell, so after the key has been on for a minute or two, turn the key off, replace the fuse, and - drum roll!! - the light is out. Be aware, though, if it was more than a hiccup in the system and you haven't corrected the cause of the problem, your light will come back to visit.

All true and accurate. OBDII became mandatory on all vehicles sold on or after 01Jan1996 in the United States, the OBDII Port must be within three feet of the driver and require no tools to access. But Toyota was a bit ahead and had it as early as 1993, in 1994 model~year cars, the Camry, Lexus, for example and others

-It is actually illegal for Autozone employees to just erase the engine code because they did it before and got sued by several people because they erased the engine code and then something went wrong with the car and the people got hurt in accidents. so they arent actually supposed to. i only know because my boyfriend works there and he and his boss explained this to me one day when i was curious about this exact thing and started asking questions.

I just had the EGR valve replaced on our 98 Accord for the second time in two years. At least the price of the part has come down a huge amount in this time - from $300 to $70 - I suppose since it is a mass produced item since so many 98 Accords have this problem. The last time the car had under 80Kmi so was under warranty but this time I paid an independent mechanic $170 which included the part. He said it is a poor design since even a speck of carbon in the EGR valve can cause it to stay open and the check engine light to come on. And he expects it will happen more often as the car gets older.

An guy who is a mechanic where I work said he thought it was best to clean out the deposits and a good product to do this was Marvel Mystery Oil (at Walmart for about $2 per pint). He said to use 4 oz in the gas tank when filling once per month for a few months. Besides possibly preventing the valve from fouling as often, this should also allow the car to run longer without needing premium fuel, according to him.

Every Honda I have had (and all I have had is Hondas for well over 20 years) has required midgrade fuel at about 120Kmi then premium at around 160Kmi to prevent it from pinging, no matter how many times I had it tuned, the plugs replaced, and the valves adjusted. The guy said the Marvel Mystery Oil will fix this, too - use it once per month until the premium fuel is no longer needed, which will take 3 to 4 months. I have no idea if this will work (it's a Mystery to me! ) but I will give it a try since otherwise this is still an excellent car.

Here is more input from others:

• When I bought the 99 Accord the salesmen told me that the Check Engine Light would come on at about 7K miles and not to be alarmed. This would be freindly a reminder to bring it in for the 1st service he said. Well just as the guy said at aproximatly 7K the check engine light came on. I called the service department and he insisted on me bringing it in so that they would perform the normal oil/filter changes then reset the light. After a bit I convinced the guy to tell me how to reset the light.

• THIS IS HOW YOU RESET THE CHECK ENGINE LIGHT ON THE 99 HONDA ACCORD. 1. With the Car Off, Press and hold down the Odometer Trip Reset Button. 2. While still pressing the Trip Reset Button, Turn the Ignition Key half way on where all your oil, check engine lights etc.. turn on. Don't turn it as far as you would to normally start the car. Wait a few seconds and the Check engine light will turn off. 3. Turn the key back to the Off position and you're done. What a scam Honda has with the BS Check Engine Light.

• In the repair book it says to remove the number 13 (clock back up) fuse on the passenger side while the ignition is off for 10 seconds. That should work according to the repair. If the light comes back on then u might have a problem.

• Two different things being addressed on this whole topic. 1. To reset the "Maint Rqrd" light, you push and hold the reset knob and then engage the accessories via the the ignition switch. 2. To reset the "Check Engine" light, you need to either pull the fuse already mentioned in previous answers or disconnect the negative battery cable for a while. (Then make sure you know the Radio Code to reset your radio unit so it works).

• The previous steps for resetting the service light and the check engine light also work on the 2000 Honda Accord. Excellent insights! Thank you! Just a note for the novice repairmen: the fuse panel is inside the passenger door on the side of the dash assembly (not under the hood).

• First you need to determine if it is a "check engine light" or a "maintainance required light" A check engine light is usually an amber light with the picture of an engine with a line through it. If this light is on you should take it to a QUALIFIED REPAIR TECHNICIAN who is capable of working on a Honda. They have all the tools needed to diagnose your repair.If it is a maint. required light new Honda"s are reset by holding the trip reset button down and turn the ignition switch to "on" while holding the button. wait until the light goes out (about 15 seconds) before releasing the button. This light will come on every 7500 miles.

• AS YOU KNOW THE CHECK ENGINE LIGHT COMES ON FOR A VARIETY OF REASONS. A DIAGNOSTIC WOULD NEED TO BE RUN TO SEE WHAT CODES ARE COMING UP. ASSUMING THAT YOU HAVE DONE THIS AND MADE THE NECESSARY REPAIRS AT A SHOP, THEN THE SHOP SHOULD HAVE RESET THE CHECK ENGINE LIGHT. IF YOU DID THE REPAIRS YOURSELF YOU CAN DISCONNECT THE BATTERY(BOTH POSITIVE AND NEGATIVE TERMINALS) LET IT SIT FOR ABOUT 15-30 MINUTES. IF YOU RECONNECT THE BATTERY AND START THE ENGINE AND THE CHECK ENGINE LIGHT COMES BACK ON, THEN ALL OF THE NECESSARY REPAIRS HAVE NOT BEEN DONE.

• All you have to do is disconnect the Negative battery terminal. It is not necessary to disconnect both. Once you've disconnected the terminal, let the car sit with no power for a few minutes, then reconnect the battery terminal. Your light should not come on, unless your engine sensors throw another code through your car's computer.

• You DO NOT need to disconnect the battery terminals. All you have to do is turn the key to the "on" position (not running, but so that the radio etc. come on) and hold the trip reset button for about 15-20 seconds. KEEP IN MIND - that the light could be an indication of needed service as opposed to just coming on based on mileage.

• To be clear, you must hold in the trip odometer reset button and THEN turn the key to the "on" position. If you prefer the battery disconnect method, be sure you have your radio code handy to re-initiate.

The best and only true way to reset a "check engine light" is not to go to Autozone or any where that has a scan tool or OBD II and have it turned off just fix the problem then a auto technican will turn it off or it will just come back on in a matter of time,

DON'T disconnect the battery your just going to reset your vehicles memory and reset all emission monitors and have to go through a drive cycle and by time it resets its going to trigger the "engine light" agian.

autozone employees are parts people. a code does not tell you what the problem is, it tells you where to look for the part, dont buy an egr when it says egr under par. look for a technical school around you, for a nominal lab fee (my school's is 12 dollars) they will do a professional diagnosis on your vehicle, and if you buy the part, they will replace it with free labor. disconnecting the battery cables and slapping them together is a terrible way to clear the code as it will only come back and it will also reset your vehicles eprom, which may decrease fuel economy.

*Holding in the odometer trip reset button in then turning on the ignition until the accessories come on only resets your maintenance required light. On a 98 Honda Accord LX under the hood left side right up against the fire wall there is a fuse box. Open the box and look for the ACC back up fuse. It's not your typical fuse, it is larger and square and on my car it is clear. Pull it out for 30 sec or so then stick it back in and go start your car. The light should go out. If it comes back on then you have a code that you need to get fix by a mechanic or something simple like a gas cap and fuel injector cleaner. When you do start your car you should have to reset your clock but everything else should be O.K. This is just to turn off that annoying light but you should get your car checked out or you might have more damage unless you know that your car is O.K. and the light just comes on......

1999 Honda Accord EX V6 Check Engine Light Comes On - Take to Autozone for Free Code Check. If the code reader diagnoses a code P1491, it indicates the EGR valve or port (Exhaust Gas Recirculation) Valve or port (located inside the driver side intake manifold on the top of the engine) has accumulations of fuel debris buildup that is clogging up the valve or port. This fuel debris buildup causes obstruction of the EGR valve or port which causes the Check Engine Light to come on. The purpose of the EGR valve is to channel unburned gas that is released into the exhaust back into the intake manifold to burn it and reduce emissions. The cost to fix this at a Honda dealership is $380.00 and a good independent shop is $180.00. You can also remove the intake manifold and clean the debris from the EGR port yourself. A much easier and less expensive way to fix this problem is to purchase S1-1 Red Line Complete Fuel System Cleaner (15 ounces per bottle) at Schucks O'Reilly Auto Parts for $9.99 per bottle. Add one 15 ounce bottle to your gas tank (one bottle of S1-1 Red Line to 20 gallons of gas) and fill your gas tank. This will clean your EGR valve and all of the fuel system. You may have to use several bottles (one per tankful of gas) to clean your fuel system depending how much fuel debris buidlup you have in your engine. After the fuel debris is removed by the S1-1 Red Line Complete Fuel System Cleaner, your check engine light will not go off. To get your check engine light to go off, disconnect your positive and negative battery cables for 30 minutes then reattach them. Reset your Honda Accord clock and enter the radio code on your radio to get the radio to work again. It took me a while to research this but it works, its easy, and it will save you money and make your car run efficiently again.

2001 Honda Odyssey: Removing the #13 "Clock Backup" fuse (7.5Amp) for 1 minute or so and then reinstalling it worked perfectly to clear the "Check Engine Light"! The fuse box is located under a small panel by the passenger side right floor kick-panel, very easy access. Keep in mind that I did the maintenance myself to properly fix the EGR problem that had caused the "EGR flow insufficient" code to make my check engine light come on. I performed the repair, then cleared the check engine light by pulling the fuse. Now I can go get my car smog checked! Thanks everybody! God Bless!

• I have an '03 Civic and I have the REAL answer right here. There's a couple of steps to follow, so here we go: 1: put the key in the ignition. Don't turn the car on or turn it. 2: next to the odometer is that little knob for the trip OD. press that in and hold it.(you'll have to hold this for the entire rest of the process, so I hope you ate your Wheaties this morning) 3: now turn the key two clicks to the II position. (are you still holding the trip button down?..you had better be..) do not actually start the car. 4: keep holding the trip button down and leave the key at the II position until the maint req'd light goes out. 5: don't get all excited. Keep that trip button pushed down while you turn the key back two clicks back to off and take the key out. 6: Ok Ok, NOW you can let go of the button. All of you that answered before, your hearts are in the right place. But the Hondas have changed since the 90s. I had an old Accord, and yes it had the little button that you can push right on the dash. But the new Hondas are reset differently. As far as I know, the proceedure I gave just now will work with any Honda, not just the Civic.

• I have a 02 civic and the only thing I did differently was start with the key in the #1 position.

• I have a 05 civic and the process above worked like a charm. (Just wanted people to know that the process works on 05 civics too)

• I have a '97 accord and on the dashpanel, by the mileage/tripomemter is a small black box like thing, the key for the car fits right in and resets the light. Look in your manual, it will say in there for sure or contact the dealer, they should know. I know the '97 accord light comes on after so many miles have passed, and most places that aren't the dealer do not reset it so it will come on and I usually reset it myself.

• I have the same problem and although I haven't tried this yet, I read in another forum that you should press and hold the select/reset button; then turn the ignition on and hold until the light goes out (about 5 seconds).

• It's easy to do. The instructions are in your manual (page 65). It's different for 4 and 6 cylinder models. I have a 6. Here's how to reset the 2003 6: 1) Put the key in the ignition without turning. 2) Press and hold the odomoter reset button. 3) Turn the ignition key to the on position without starting the car, continuing to hold the reset button. 4) Hold the reset button until the light goes out - approx. 10 seconds.

• Take it to the auto parts or the dealer if it is not in your book and have them reset it with the computer, or disconnected your battery.

• Disconnecting your battery for a few seconds is a quick and simple way to reset the trouble codes in the computer.

• I have a 2000 Honda civic, all I do is use a pen or key and push in the the slot beside the maintenance light. Not sure if you have that but you just hold it down and it flips itself.

• I was lookin for the owners manual in this customers car and couldn't find it but your directions worked for my customers 00 Civic 4 cylinder also. NOTE Disconecting the Battery does not work and will also not reset almost any light in Cars that are newer then 1996 from what i have found. (OBD2 Systems)

• Attention, when you disconnect the battery you may reset the radio anti-theft code and if you don?t know it you get into more trouble.

• Ok first off the battery disconnecting "thing" does work but you have to disconnect both terminals and touch them together for 10-15 seconds for it to work. And I seem to se alot of people just wanting to turn the maintenance light off, it says maintenance required i suggest you get your maintenance done, that's why it's there. And for any of the non-car type people out there if you take your car to any dealer they will tell you waht need to be done and why the light is on free of charge... at least i know i would at my dealership. It's not that hard. Oh and as for the radio lock code it is again a simple phone call away for any dealer and you should not be charged for it. If someone is telling you otherwise then you should ask for the service manager or shop forman and they will get it done for you.

• The solution for the 2003 V6 did work, Thanks. The dealer stated at least for a 2003 Accord this light will reappear every 7500 miles.

With a p0455, the most common repair is to:

• Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
• Otherwise, replace the gas cap, and/or
• Inspect the EVAP system for cuts/holes in tubes/hoses that run from the fuel tank to the engine (you may hear a vacuum noise or smell fuel), repair if necessary

I hope this clarified the other misinformation which is currently published and posted on the net (regarding this subject).

Okay, pay attention please, you need to disregard that entire answer that obviously the person who wrote it made there own assesment, not according to the facts. Service engine soon is Nissan's and other manufacturers check engine light, yes they are the same. The light means your vehicle needs an engine diagnosis to pinpoint one or multiple problems. These codes appear because the emmissions, ignition and overall performance of the motor is compromised. The problem could be a run down sensor, vacuum leak or ignition(timing) problem. The code will get you looking at the right system on the vehicle but not always the exact problem. Good to pay engine Dio if unsure.

Go to auto zone and have the codes read for free.

hello fellow light watcher. my light came on in the fall of 2000. my machanic said i needed a jump( ok the computer said that) and he was confused. so off to the dealer i went. their computer said it was an internal sensor (not covered) i asked at the time how much was that? they said $400.00. i then asked what would happen if it was not repaired? well they said i would stall on the highway. i very calmly put up eight fingers and counted then by 50..( my est. on calling a tow truck for a jump) "well after i stall eight times i guess i can kick myself for not getting it done." it is now five years later the light i believe burnt out. my machanic mentions is when i go in for any service, he laughed when i told him it wasn't on any more. oh and i have yet to stall out or need any kind of jump-start.

At least in Texas you can't pass state vehicle inspection if this light is on. H+++

Pull the codes from the computer, match the code to the troubleshooting procedure, follow the procedure to find the source. Repair the source, light will go out if that was the only problem. There are "monitors" or self tests the computer runs the car through a drive cycle, if a problem occurs, it may not run all of the self tests until that problem is taken care. Therefore, another problem may exist. It is emission related. OR hook up a scanner that is capable of clearing codes, and hope that none are still active.

The " check engine light" is by far one of the most misunderstood technological advances by the public. This is an needed in-depth understanding for the public. It is a warning light that is illuminated when there is a problem affecting the EMISSION SYSTEM only. Emission system being the pollution control system. Don't get a hard on against it as it is a good thing once you understand it. One point that was brought up a a recent meeting of technicians was that the amount of hydrocarbons is greater when the gas cap is left off than when the engine is running. Hydrocarbons are part of pollution emitted as gasoline evaporates. Going a step farther, one facet of the emission system is the "Evaporative" portion. This is when the fumes from the gasoline are leaking from the system into the outside air. This is one part of the emission system that can trigger a check engine light. I would say that about 7% of the vehicles that have a check engine light are the result of a loose or inadequate gas cap. But understand that many scenarios are possible with the "check engine light" The vehicle's powertrain computer (note that some vehicles have 17 different computers) will run a series of self-tests. They will only run under certain criteria. And they can be vastly different from manufacturer to manufacturer. Some self-tests are not run until preceding ones have run successfully. So if there is a problem in one particular area that is preventing another self test from running, you can have a situation where one problem is fixed, but another still exists. If you fix a problem and drive the car through a drive cycle that sets the monitor (or self test) the light will go off as it passes that criteria that triggered it in the first place. After 1996, the auto industry went to a idea called OBD II (on board diagnostics). This was to get all the manufacturers onto a similar plane for troubleshooting and powertrain control. While they still differ vastly, many corrections and adaptations were made for technicians to better fix the check engine light problems. Prior to this there were so many different and poor troubleshooting data from a check engine light problem that resolving the problem was much more difficult. Many early warning light of this nature were set to illuminate based on mileage. An Oxygen sensor was one of the things that were meant to be replaced when that mileage was hit. This is much like many current "Change oil lights? that are set based on a pre-set mileage.

I have a 1995, not 97, and none of the things you have mentioned has anything to do with my light.My light has to do with the EGR Value, it is clogged.Needs to be replaced, but does absolutly NOTHING to make the car run bad.The light can be reset,but it will eventually come right back on, until the EGR value is cleaned or replaced.MOST, EGR values get clogged with carbon,and DONOT break,(unless you have the plastic type,it can crack)therefore if you was to go purchase some carborater cleaner. remove you EGR value and cleaned completely,you have a chance of the light going off.If Not you probably have a sensor clogged or defective.Taking the light is could be risky,if you ignor a problem too long it could make more things go bad and cost you more in the long run.A Ford Taurus, MUST BE ERVICED TO SURVIVE, it's not the best car in the world.It's only as good as the machenic or person who takes care of it. Can you answer the question:WHAT IS THE MOST IMPORTANT PART OF THE CAR? Yeah yeah yeah, you said engine,or some other thing.But the answer is not enigne,IT'S FLUIDS, If you' just keep your fluids up and full you'd be ALOT happier.

It will be impossible to give you any better than a broad answer here, because there are literally hundreds of possibilities as to why a malfunction indicator lamp(MIL) comes on. The system would have to be scanned to retrieve whatever fail codes there are. Then we would use a manual (that is literally 3 inches thick)that contains flow charts with pinpoint tests, using a voltmeter, to hand diagnose, and find out what is wrong. This process can take a few minutes, it may take a couple of hours, depending on what is actually wrong.

Now here is the "why" of a MIL: What is actually turning on the MIL is the Powertrain Control Module(PCM), commonly known as the engine control computer. Inside of a PCM there are actually two separate systems. One is control, the other system is diagnostics. PCM diagnostics acts as "big brother," constantly looking over the shoulder of the control side of the PCM. Diagnostics is constantly monitering systems to see if the expected voltages and values are present.

Here is an example: If the PCM diagnostics knows that it has been so many minutes since the engine was first started, then the engine temperature should be around 195 degrees. In our senerio, if the engine is still 160 degrees, it sees a problem, and sets the MIL. The technician has to use pinpoint diagnostics to see if we have a stuck thermostat, if the Engine Coolant Temp(ECT) sensor if sending a false signal, if the wiring between the ECT and the PCM is bad, or if the PCM is faulty and interpreting the signal received from the ECT incorrectly. But the PCM is not capable of monitering everything all at once, so it basically goes down a checklist, over and over again, as you are driving down the road. Sometimes a problem can come and go intermittantly, at the right times so as to avoid detection by the PCM.

That is why sometimes a MIL doesn't always come on everytime there is a problem. Sometimes you can unplug a sensor even while the car is running, and it takes a while for the MIL to come on, just because the PCM diagnostics hasen't gotten back around to looking at that area yet.

Our senerio only talked about one area that a PCM moniters. There are dozens of sub-systems that the PCM looks at, and dozens of possible failures within each of those sub-systems, that could cause a MIL. answer The two main causes for the engine light to appear lit up are (1)gas vac sensor, (2) the pip(at least that's what it is called by my mechanic). The gas vac sensor is responsible for the engine light coming on in every make of vehicle, especially in Dodge's. It is caused by turning the gas cap either less than three clicks or more than three clicks. It causes a disruption in the vaccuum and kiccks the gas vac sensor to light up the check engine light. Disconnect the battery for 30 minutes, loosen the gas cap and replace it by turning it three clicks exactly. Best way to prevent this problem is not let the gas jockeys replace your gas cap after fueling. As for (2) the pip is a very common problem for engine light on Tauras' with 3.0L engine. The pip(in where your distributor is)twists and causes the sensor to break apart thus causing the engine light to light up. I'm no mechanic but the one I go to used to be an engine specialist with GM so I take his word as gospel. He's never been wrong yet and saved me a fortune.

I just took the positive terminal off the battery for 30 seconds which reset the computer and the "service engine soon" light was no longer on. I assume that whatever caused the light to go on in the first place is no longer tripping the warning.

take the battery cables off and put them back on.

The check engine light (CEL for short) is triggered when one or more of the many sensors on the vehicle detects a not-normal reading,

There are 2 basic steps to determining the cause of the CEL coming on:

1. Have the codes read - many places offer to read the engine codes for free. Autozone even provides a printout of the codes, and a short description of common causes
2. Research those codes! Find out the true cause and reason for the not-normal reading. It is not often that the sensor itself is bad and requires replacing.

There are countless sources of information on engine DTC (diagnostic trouble codes) on the internet - including Wiki s!

Pay attention to those check engine lights - they're there for a reason. And with the internet today, you can readily find the information to keep your car healthy, and even save some $$ in the process.

No reset button. Easiest way is to disconnect the negative battery cable for a couple of minutes, then reconnect. This will erase any codes stored in the computer. If everything is okay, the check engine light will stay off.

disconnect the positive terminal on the battery for 30 minutes,this will drain the ecm. after 30 minutes, reconnect the terminal, start engine, and hold at least to 750 rpm for five minutes

Use an OBD code scanner, find out what's wrong, fix the problem then, if necessary, clear the code with the code scanner. Often just replacing the faulty component will solve the problem, other times you need to clear the code manually.

You must have an OBDII code reader to turn of the light.You can save money by going to your local autoparts store.They can tell you what made it come on and then reset the light.

Repair the problem that caused the light to come on, and reset the light with an OBD2 scan tool.

You can disconnect the battery for about 2 minutes and then connect it and start it and it should clear.

try disconnecting the battery for about 10 mins. If this does not work have vehicle scanned to determine problem or have codes cleared--most auto part stores will do this

try completely disconnecting the battery for a minimum of 30 minutes.

Disconnect the battery and then reconnect it. Or bring it to an auto parts store and they can hook it up to the tester that they have for it, tell you what's wrong with it, and then it will reset.

The ABS (anti-lock brake system) light comes on because the computer has detected a problem and set a code. The code will stay in the computer even if the light goes out. You need to have the system Scanned for codes. Once the cause of the code has been repaired the light can be shut off by clearing the code.

Most auto repair shops will have Scanners and all the equipment to Diagnose and repair the problem. And, Most auto parts stores can plug in a diagnostic scanning device into your vehicle to read the trouble codes at no cost if you purchase the parts necessary to repair the vehicle from them. The trouble codes can tell you THE AREA where the problem is with your ABS system. So it's wise to have a Tech check that circuit to isolate what the problem actually is.

In order to reset this light you need to have access to a Scan tool that does more than just read the codes. Other diagnostic equipment may be needed as well.

You have a problem with the ABS. As long as the light is on the ABS is not working. The light will remain on until the problem is fixed.

ABS = Anti-Lock Brake System

If you have this light come on while not braking, it most likely means there is a problem with the electronic controls in your brakes. If it comes on while you are braking, it means the Anti-Lock has kicked in. It should only do that however, if you are braking really hard. Addendum: It is very important to have the above procedure done to diagnose the cause. It might be minor but it could be as important as a wheel bearing, and a cracked hub, which if damaged could cause the wheel to become loose and you could lose control. I've added this addendum because I was told by a mechanic not to worry about the ABS light, that it was a minor problem. Only to find out later that in many vehicles the ABS sensor is attached to the wheel hub and a malfunctioning bearing can cause the sensor to slip., causing it to turn on.

Usually it is the mass air flow sensor or the O2 sensor. Also, the theft system is known to turn the engine light on.

Why guess when you can go to Auto Zone or other parts stores and have the codes read for free.

Mine Came on after about 100,000 miles and it was just dirty spark plugs. Changes the plugs and the wires and it never came on again. Car was stuttering when going up hills and it fixed that too.

A loose, cracked, or defective gas cap may also be the culprit.

Mine was a small 4.5 inch vacuum hose that was cracked, located right in front on the top of the 2.4L engine. It is an easy & cheap thing to check before replacing sensors.

transmission fluid level is low

- I had a temperature sensor malfunctioning and sending a poor mixture of fuel to the engine. When I was accelerating a lot the engine would hesitate and jump. Repair was $200 and works fine now.

I had the same problem with my 2002 Malibu and had to have the catalytic converter replaced in it. You would have to visit the dealer to make sure, because advance or other similar stores cannot tell you what is wrong with it. A sure sign that it needs replaced is if the check engine light stays on and your losing power.

I had a 0403 error on my 98 Malibu and one place said it was the cat converter and both O2 sensors and wanted $550 took it to another place and they said it was just the cat converter and replaced it in 25 min for $220. That fixed the problem and I passed inspection ok.

Just to correct the one above me, I'm assuming that was a P0430, as p0403 would be an EGR code. And most places will not warranty a cat if you don't replace the O2 sensors with it. And not all cat failures involve low power, that only happens if they clog. To answer the original question, there are hundreds of reasons why the CEL can come on. And the theft system will not set a check engine light, though it can store a P1626 in the PCM for excessive cranking. That code doesn't request the check engine light though.

The previous answer was good for high dust environments (and if you have a Ford Van all environments are to be treated as high dust) but for those of us in high corrosion environments, consider the following:

If you have an Explorer (Or Ranger/Mazda B-series) check for a broken wire near the left side framerail near the rear axle.

If you have a Hyundai (including Kia), Nissan (including Infinity) or Toyota (including Lexus or Scion) you should disconnect the electrical connector and then apply and remove 12V power to the vent solenoid/valve. The difference between 12V applied and not applied should be the difference between not being able to blow through it and being able to. After testing at least 5 times, if it fails even once, replace the solenoid/valve.

In the case of Nissan or Toyota, if replacing solenoid/valve it is usually best to replace the canister as well as you might inadvertently break the canister while replacing the solenoid/valve. With many Nissan vehicles, it is almost impossible to not break the canister without using techniques involving unreasonably high fire hazard.

Hey Brian==It is probably the gas cap not on tight. Have the codes removed and see if it comes back on after you tighten the cap.GoodluckJoe

Well, my experience with a 2000 GMC 3/4 ton truck says otherwise.

A loose gas cap will not give you P0446 because that is the code for a failed vent test.

Here's how it works: To check the vent system the engine vacuum valve is opened at the same time as the charcoal filter vent valve is closed. This creates a vacuum in the gas tank and when the vacuum reaches a certain level, the vacuum valve closes and the vent valve opens and a timer is started. If there is a restriction in the vent valve or it doesn't operate electrically, the tank fails to re-pressurize within the correct time and you get a P0446.

Here's what I did: I removed the vent valve and found it choked with a fine dust. I cleaned the valve, but noticed that there was lots of dust in the tube running down to the charcoal cannister and realized the gravel filter in the vent valve is useless at stopping dust. I took out the cannister and discovered an amazingamount of dust clogging it up. I cleaned the cannister by holding it vent side down and sharply tapping it many, many times it while blowing air (at low pressure) through it toward the vent side until it passed air freely both ways. Did I mention that there was an amazing amount of dust that came out of the cannister? I would think that gasoline residues from overfilling might clog up the cannister too, but that didn't happen in my case.

Below are what I consider the possible causes of P0446 in the order of least likelihood (IMO) for a vehicle used in a high dust environment:

Electrical vent driver circuit in computer burned out (especially if the vent valve is shorted), electrical vacuum valve driver circuit burnt out, vent valve coil open or shorted, vacuum valve coil open or shorted, bad vacuum sensor in the gas tank, vent valve filter clogged with dust, charcoal cannister clogged with dust or residues.

Removing and replacing the vent valve and especially the charcoal cannister in a GMC truck is a major, major pain in the a-- because the entire vehicle was carefully engineered by GMC so as to make replacement as difficult as possible. It does no good cleaning and replacing a clogged vent valve as the cannister will be clogged too. A new cannister is about $175, but a cleaned one is free.

BTW, my vent test works perfectly now. Added by Protoart: If you have the P0446 code and the vent valve is bad, don't continue to drive, or you will clog (saturate) the canister with gas for sure. My wife's 05 Scion, check engine light w/ P0441,0442, and 0446.......cleared with my scanner, never came back after I tightened the gas cap