Check Engine Light

The check engine light comes on in a car when the engine is experiencing a problem. Ask questions here about your car's check engine light.

13,206 Questions
Oxygen Sensors
Ford Ranger
Honda Civic
Check Engine Light

Why does the check engine light come on and how do you reset it?

The "check engine light" is a warning light that is illuminated when there is a problem with the EMISSION SYSTEM only. Emission system being the pollution control system. It is a good thing once you understand it.

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The " check engine light" is also known as a malfunction indicator light (MIL). You can disconnect the battery red lead for about 5 min and it will reset. However, if there is a hard fault, it will come back on.

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Disconnecting the battery won't do the trick on OBD 2 vehicles.

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Without a scan tool designed to reset the electronic control module (ecm) a do-it-your-selfer can't reset the check engine light.

Pull the codes from the computer using an OBD (II) code reader. Match the code to the troubleshooting procedure, follow the procedure to find the source of the fault. After you have repaired the fault, the 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.

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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 lights of this nature were set to illuminate based on mileage. An oxygen sensor was one of the things that was meant to be replaced when that mileage was hit. This is much like many current "Change oil lights" which are set up to come on after a pre-set mileage.

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Great question and good answer above. There is one thing to add however. On my 2004 Buick for example I am required to manually reset the "check oil" light myself every time I get an oil change. This ensures that the system understands the condition the oil is in. If/when I do not reset it, not long after my expected date the light goes on by default as a reminder.

Your instruction manual would outline this. Mine for example is simply...

1. Insert key

2. Turn key to ON, without engaging engine (just before the engine cranks, and leave key there)

3. When placed to ON, press and depress the brake slowly 5 times in 5 seconds.

4. Turn key to off.

5. Turn key and start engine.

The check engine light is now reset, if it returns shortly it is an actual issue, rather then a reminder.

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Some Ford Mondeos have a 'Service interval expired' warning light. It is pretty much the same as the "check oil" light mentioned in the answer above.

On that type of Ford Mondeo there is a small hole in the display screen in front of the 'Service interval expired' warning light. To reset it, just turn the ignition key until the all warning lights come on but do not start the engine. Then press a tiny button in the warning light display panel by poking a straightened metal paper clip through the hole. If you hold it steady for 10 seconds whilst keeping the ignition on, the warning light goes out. It will come on again when the service time period again expires.

203204205
Check Engine Light

What does the 'service engine soon' light mean?

Engine controls:

All vehicles equipped with fuel injection systems have computerized engine controls. These systems maintain the best driveability and performance at the lowest emissions. The Computer (ECM) relies on sensors (O2 sensors, MAF, ECT) and actuators (EGR valve, IAC valve, Fuel Injectors) to get the job done. The computer uses the sensors input to make calculations and then sends signals to the actuators to control their operation. When the service engine or check engine light illuminates, it is because one of the sensors has detected a "fault" (an abnormal condition) and so the ECM triggers a "trouble code" which causes the light to illuminate. Generally, the ECM then ignores the input from the affected sensor until the reading becomes normal again, and the light will go off. The first step in clearing the trouble code is to retrieve the code and find out which sensor has a problem. On 1995 and older vehicles (OBD-I) ground the diagnostic terminal on the ALDL and turn the ignition on. 1996 and newer vehicles (OBD-II) are much more complicated and require at very least a handheld scan tool. DO NOT START IT. Many diagrams of how to go about this process are available all over the internet by searching for "service engine soon." The service engine light will first flash code 12 three times, then the trouble code three times, then code 12 three times again, and so on. After retrieving the code, check the operation of the sensor by using a multimeter. If the vehicle has more than 100k miles, replace the sensor, it is worn out. If the sensor checks out the process becomes tricky, and requires a thorough knowledge of engine performance concepts. But this information will give insight into how computer systems work and help you deal more competently with your technician. Notice the word technician--shade tree mechanics can't work on computers.

Sensors:

The reason the "Check Engine" light comes on is because one of the sensors attached to your vehicle's engine is throwing a signal to the car's computer saying that there is a problem. The problem can be found by plugging into the car's diagnostic port and finding the error code, then fixing the problem. There's one problem with the old "plug a paperclip into the diagnostic port and read codes" trick-it only works on pre-1995 cars, which use OBD1 systems. Cars 1995 to present are OBD2, which require that you use a code scanner. You can purchase a code scanner at just about any car parts store, which can be rather costly and is recommended to be left to having a qualified tech do a computer scan.

The " check engine light" is by far one of the most misunderstood technological advances It is a warning light that is illuminated when there is a problem affecting the EMISSIONS of the vehicle.. Don't let it bother you as it is a good thing once you understand it. One point that was brought up 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 a small percentage 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 multiple computers aside from the powertain computer) will run a series of self-tests. They will only run under certain criteria. And they are different from manufacturer to manufacturer. Some self-tests or monitors 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. There are many different sources for the light to come on. Anything that caused combustion to fail, commonly called a misfire will set the light. Various sensors such as oxygen sensors that evaluate the exhaust before and after the gases are burned in the converter. Transmission codes may set the check engine light to appear. If the car is running okay, get it fixed in a reasonable amount of time such as within the month. It will probably save you fuel if you do. However if the Check engine light is flashing, you should be driving it as damage is being done to the converter. Some emission components are covered beyond the standard warranty. The converter for example is covered up to 80,000 miles by the manufacturer.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, 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. To start testing for the check engine light, you'll need to find 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. There are self-tests for the oxygen sensor circuit, egr system, evaporative system to name a few. Therefore, another problem may exist. It is emission related. Or try to hook up a scanner that is capable of clearing codes, and hope that it won't come back on. But don't bet on it. Lastly, disconnecting the battery in some cars will clear the memory of the computer and may temporarily turn the light off. Beware that this may also cause other problems such as the car not rembering it's idle and will have to relearn it, the radio may be rendered inoperative or in the case of the new Toyotas, the air bag can blow.

207208209
Transmissions and Drivetrains
Check Engine Light
OBD Diagnostic Codes

What is OBD code P0700?

P0700 is EATX code present.

It simply means that the engine computer has noticed that the transmission computer has a dtc in it. This causes the Pcm (engine computer) to turn the check engine light on. You will need to have the TCM (trans computer) checked for codes to know what to diagnose.
General automatic transmission fault. It could be a sticky internal sensor. A transmission shop could read the actual fault from the transmission.

191192193
Dashboard Lights and Gauges
Check Engine Light
Lincoln LS
Oldsmobile Calais

What could be wrong with a 2000 Lincoln LS if the engine light on the dash will not go off?

To find out what is wrong with it you will have to take it to a repair shop or the ford dealer with a computer to hook it up, but the engine light being on something is wrong with the car, it kinda sounds like a ingition coil pack going out, if so it will only get worse and could also be many other little things, but it must be repaired before the light will go off, and needs to be repairs ASAP so it doesnt cause anymore damage, that is why the light came on is for it to be serviced and repairs ASAP.

I have the same problem with a 2001 LS V8 sport. They diagnosed this earlier this year when I felt a subtle pulsing in the car during heavy acceleration. They said they must change both according to Lincoln service number SSM 512 481 091 and replace BOTH pumps (which shocked me to find there was two). They listed the pumps as YW42-9275-BC and YW42-9H307-BA. Apparently these cross reference to part number E2274M from Airtex but I'll know more soon as it is on order from my local jobber. I do know that if you order a 'pump' from A/C number MU2013 you will get a sender unit only which is listed improperly (and probably why the Airtex costs about 25% more). One other item the dealer replaced on my LS was the Idle solonoid but that shouldn't impact the car while driving, just while idling.

199200201
Check Engine Light
1995-2005 Chevy Cavaliers

Omg engine light is on stays on but car runs fine?

When the check engine light is on it simply means that the computer has detected a problem somewhere. You'll need to take the vehicle to someone who can read the computer fault code or take the vehicle to an automotive parts store that will allow you to borrow, rent or buy a code scanner.

Don't try to guess what's wrong, you'll just get frustrated and put a lot of unnecessary parts in your vehicle.

Other responses have been moved to the discussion page.

193194195
Check Engine Light
Subaru Impreza
Ford Explorer XLT

Why is your check engine light and cruise control flashing on a 2007 Subaru impreza?

When your check engine light comes on in a Subaru, it disables the cruise control (thus why it is flashing). Take it to your local dealer, it's still under warranty. Check Engine light comes on due to a wide range of possible problems, automatically disabling the cruise control as mentioned above. The problems can range from sensor issues (MAF, Oxygen Sensors, Etc.) to a loose gas cap, to condensation, to a loose connector on a sensor, perhaps even a dying battery, a flaky alternator or a faulty battery terminal connection. It is a catch-all problem indicator. If you are lucky, you can simply reset the ECU by disconnecting the battery for a minute, and the Check Engine light will be gone and cruise control will work. If the error persists, you need to get the error code (if you do not have a code reader or accesspoint, stop by Autozone or somewhere similar and get them to read it for you) see what the error is, and fix the problem. Simple? Hopefully it's not something more troublesome, bad injector, etc.

130131132
Check Engine Light
VW Golf
VW Golf GTI

How do you reset airbag light for a 98 vw golf tried disconnecting battery light still onlight came on after replaced ing switch?

You have to repair the cause of the light coming on. The airbag computer will have set a code about the cause. See related question for more info.

179180181
Cars & Vehicles
Auto Parts and Repairs
Emissions and Exhaust Systems
Check Engine Light

What part would make your car not pass smog regulations because of hydrocarbons?

Perhaps this may help you in your search for causes. A high hydrocarbon reading is usually unburnt fuel. If the CO reading and the NOx readings are below the limit then look towards an ignition problem as being the most likely culprit. As the prior answer suggested, start checking items and begin with the basics. Year, make model, engine size, options, symptoms etc will help you get a more accurate answer next time.

Check the plugs first, all of them! One bad plug will give you a miss and everytime the car misfires unburnt gas goes into the cylinder and out the exhaust which raises the HC. Same goes for the wires (check resistance with a multimeter) check the distributor cap & rotor (if applicable) for cracks, corrosion or burnt areas. Might want to do an injector service (if applicable), a sticky injector might put fuel in at times when its not supposed to and up goes the HC. If the check engine light is on 1st thing to do is pull some codes and this will give you some direction. Codes can be pulled manually by using the diagnostic connector or a scanner.

Answer

High hydrocarbon levels are also seen with a much too lean mixture. If you are looking at an older carburated car, check this first. A lean mixture will not burn completely, and unburned mix goed out the tailpipe. An overly rich mixture burns fine, but to carbon monoxide, not dioxide. So a rich mixture will fail on CO, not HC. This is the reason for the vacuum hose fix - it cuts down the amount of air entering the engine, while leaving the fuel the same ( or increasing it a little if the leaks are really bad ). This said, the ignition system is also suspect, as any misfire will increase HC. So, check your vacuum hoses (lightly spray connections w/ carb cleaner, an RPM increase means a leak), change your plugs and wires if they're more than a year old, and richen the mixture a hair if this adjustment is available.

More Information:

I had to replace a lot of vacume lines to get mine to pass. It also could be o2 sensor, bad spark plugs, rich idle(too much gas), bad spark plug wires, bad injectors(or carburetor), bad ignition coil/cap/rotor(weak spark), bad catalytic converter/clogged muffler, exhaust leak, etc.

179180181
Oldsmobile
Chevy Blazer
Check Engine Light
Ford Expedition XLT

What needs to be done when check engine light comes on in your 1990 Oldsmobile 88 Royale?

Take it to a mechanic who will use a computer to read a problem code generated by the car's computer. He will repair the problem and reset the light.

Plain English problem codes are not used to encourage car owners to take their cars to the dealership for repair. However, any competent mechanic will have the handheld computer required to read the codes.

AnswerPull 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.
175176177
Check Engine Light
Late Model 1979-New Ford Mustangs
Lyrics and Sheet Music
Definitions

Trouble code p0440?

Trouble code P0440 means:Evaporative emission control system malfunction

165166167
Carburetors
Check Engine Light

Is gasoline blue?

It would be blue if it's got 2 cycle oil in it like for a weed eater or chainsaw

165166167
Chevy S-10
Check Engine Light

Where to check engine codes on 2000 s10?

Goto autozone or advanced auto. The plug is under the drivers side dash right above the pedals. They will even give you a print out at advanced auto parts store.

165166167
Check Engine Light

What does it mean when the service awd light comes on?

It means there is a problem with the AWD system or regular scheduled maintenance is required. Your owners manual will list any scheduled service it may need. If you see no service is needed then you have a problem. Seek professional help.

163164165
Dodge
Plymouth (car)
Check Engine Light

What is trouble code P0700?

P0700 : EATX code present. It just means that the transmission computer has a code in it. You need to have the TCM checked for codes also.

You then fix the trans code and reset the light with a scan tool.
P0700 is EATX code present. It simply means that the engine computer has noticed that the transmission computer has a dtc in it. This causes the Pcm (engine computer) to turn the check engine light on. You will need to have the TCM (trans computer) checked for codes to know what to diagnose. transmission control system (MIL Request) generic on board diagnostic code
P0700 : EATX code present. It just means that the transmission computer has a code in it. You need to have the TCM checked for codes also.

163164165
Auto Parts and Repairs
Ford Explorer
Check Engine Light
VW Jetta

How do you diagnose a Check Engine Light what does it mean and how do you reset it?

The Check Engine light is on because the computer has detected a problem with the emissions control system. Unless you fix whatever has caused the computer to set a fault code, it will come right back on. Depending on the model year of your vehicle and weather it is an OBD1 or OBD2 system, disconnecting the battery for a few minutes may reset the light, especially on an 1995 and older OBD1 system. Rarely will this work on a OBD2 system. On an OBD2 and some OBD1 systems, you need a scan tool to reset the light. Take it to any auto parts store and see if they will scan the system for you, free of charge. Depending on your state, they may accommodate you. The code they find will help to determine what is wrong. If you purchase the repair parts from them, they may reset the light after you make the repair. One thing to do before any of this is to check your gas cap. A loose gas cap will set the light. If you find that it was loose, tighten it, (3 clicks). The computer will turn the light off after a few driving cycles if that was the problem. == my 2 cents == The " check engine light" is by far one of the most misunderstood technological advances It is a warning light that is illuminated when there is a problem affecting the EMISSIONS of the vehicle.. Don't let it bother you as it is a good thing once you understand it. One point that was brought up 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 a small percentage 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 multiple computers aside from the powertain computer) will run a series of self-tests. They will only run under certain criteria. And they are different from manufacturer to manufacturer. Some self-tests or �monitors� 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. There are many different sources for the light to come on. Anything that caused combustion to fail, commonly called a misfire will set the light. Various sensors such as oxygen sensors that evaluate the exhaust before and after the gases are burned in the converter. Transmission codes may set the check engine light to appear. If the car is running okay, get it fixed in a reasonable amount of time such as within the month. It will probably save you fuel if you do. However if the Check engine light is flashing, you should be driving it as damage is being done to the converter. Some emission components are covered beyond the standard warranty. The converter for example is covered up to 80,000 miles by the manufacturer. 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, 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. To start testing for the check engine light, you�ll need to find 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. There are self-tests for the oxygen sensor circuit, egr system, evaporative system to name a few. Therefore, another problem may exist. It is emission related.

== Answer == Before you do anything, go to Autozone and use their loan a tool program to chech out an OBD-II code reader. Follow the instructions on the box, or if you don't feel comfortable doing it yourself (it's really easy), have one of the store employees do it for you. My check engine light came on this past winter, and it turned out that one side of the engine was too lean. I remember the light came on when I started the explorer on a particularly cold day. Anyway, once you reset it, it probably won't come back on unless there is something wrong with some component.

== Answer == Take it to a garage and have them fix it is about the only way without "special tools". Otherwise: 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. Disconnecting the battery can create other headaches and will not likely solve your dilemma. Best bet is to contact the local snap-on dealer and have him refer you to a known good shop that specializes in this technology-he will know.

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.

That is not entirely correct. An o2 sensor will not trigger a trouble code just because it has reached a preselected mileage. If the trouble code indicates a faulty o2 sensor it generally can be confirmed that it is faulty or something causing the trouble code such as a broken wire. To say that the check engine light is for emission system only is incorrect as well. The cars computers monitor a variety of things such as the air fuel mixture. The O2 sensors monitor the exhaust to ensure the proper mixture is accomplished. If you have an O2 sensor that has failed the computer will set the check engine light and not allow the system to go into "closed loop". This is when the computer will monitor a number of sensors like the "throttle position sensor" the "O2 sensors" and allow the computer to adjust the air fuel mixture. If the check engine light is on the engine will run a predetermined program and not make adjustments to provide the best performance and fuel economy. I think the best thing is to find out what trouble code has set the check engine light with a scan tool or have a tech do it for you. If it is an emission code that may not rest, such as a loose gas cap, then clear the code and see if it resets. If it resets, find out why and repair it.

159160161
Check Engine Light
Kia Sephia
Ford Explorer XLT

Why would the check engine light be on while the OD off light blinks off-and-on on a 1999 Kia Sephia?

It has to do with emitions. Your sensor is either bad or one or you plugs are bad. Change your plugs first then disconnect your negative cable from your battery for at least 20 seconds to reset your trouble lights. If that does not clear up the problem change your catilitic converter sensors and clear your trouble lights again. try replace the vehicle speed sensor in the transmission, that should take care of the problem.

155156157
Emissions and Exhaust Systems
Check Engine Light

Will a bad egr valve cause check engine light to come on?

It can.

153154155
Chevy Suburban
Check Engine Light

How do you reset check engine light 2000 suburban?

you need a scanner

153154155
Crankcases and PCV Valves
Ford Ranger
Check Engine Light
VW Jetta

How do you reset the check engine light on a 1997 Mazda 626?

"Disconnect the negative terminal and push brake pedal for 30 seconds" worked great! One note: You must use actual key to unlock doors after battery disconnect to reset car alarm so car will start.

I recomend getting the car checked out by a professional. And you never unhook the positive battery cable first, you always do the negative firstl. And sometimes when you do this it erases the computers memory. so take to a professional.

If you HAVE TO, disconnect the negative battery terminal. Put your foot on the brake pedal for 30+ seconds.

I tried the previous answer of removing the negative battery cable, and holding the brake pedal for 30 seconds and it WORKED!!! Just got back from the emissions test, and passed. THANKS!!!

I got check engine light problem just happened few hours ago, my car is 1999 Mazda 626 ES, and I tried the previous answer of above- revmoving the negative cable as well. It REALLY WORKS. It saved my time & money ^^

[Apr 27, 2008]Just applied this method "disconnect the negative battery terminal. Put your foot on the brake pedal for 30+ seconds.", it just worked perfectly. Save me lots of worries and trouble to send the car to mechanics. Thanks so much to the one who posted this method.

i just used removed the negative battery and stepped on the brake for 30 seconds on my 2000 626 es and it worked! saved $80

Just did wt u said and it really works...thanks a million

Same thing works on a 2006 MX 5 Miata....light came on due to loose gas cap and I sure did not want to pay the dealer to reset the dang thing.....Advisable to check out why you have the light at AutoZone or most other parts houses before you reset the light.

a car scanner can help you.

153154155
Rules of the Road
Check Engine Light
Safe Driving Techniques

5 Smith rules of driving?

Aim high in steering - The farther down the road you see while driving (and he's talking about "seeing, not just looking"), the less likely you are to have a wreck, he says, adding "Be aware of what's going on around you." Keep your eyes moving - Eye movement helps keep you from getting into a driving trance, the fixed stare of the driver whose mind is elsewhere while her/his ton of metal is moving at up to a 100 feet a second. Eye movement makes drowsiness less likely, too, and makes it more likely you'll frequently check your rear-view mirror. Get the big picture - Practices one and two help you stay aware of what's around you, but there's more, including road conditions, weather, and any changes in the condition of your vehicle, including fuel level, engine temperature, electrical systems, and any abnormal vibrations or sounds.

Make sure you are seen - You can't assume other drivers are aiming high, keeping their eyes moving, and getting the big picture. They may not have noticed that you're hurtling in their direction. Having your headlights on makes you more visible and they take no extra fuel, Ronald notes, so, "Turn 'em on," day and night. Even then, though, don't assume that other drivers have noted your presence or your turn signal that's blinking or even, heaven help us, the red light facing them as you both approach an intersection. Leave yourself an out - Where can you go (to the median? to the shoulder?) if something happens suddenly just ahead of your car? If you've been aiming high, moving your eyes around, and getting the big picture, you're more likely to know what to do when faced with the need for a sudden change in flight path. "Always try to have an escape route because it matters little who is right or wrong in bad situations, staying out of any 'mess' is the very most important thing," he writes.

697071
Spark Plugs and Wires
Fuel and Fuel Intake
Chevy Silverado
Check Engine Light

How do you repair Multiple Random Misfire?

I guess Autozone's free check engine light check wasn't free. But it sure make a great guessing tool for them to sell parts! PO301 is the code your refering to. I would try a professional fuel injector cleaning. even if it doesn't solve you proiblem your at least getting somthing you need. You may have leaking injector orings or plugged injectors that are beyond cleaning. Bad Wires can also set this code.

Actually, SAE code P-0301 is a cylinder #1 misfire. Multiple cylinder misfire is P-0300. Only the lowend scanners make this mistake.

However, leaking fuel injectors may be causing this as well as worn plugs or wires. Also consider fuel age and quality. You can go to the same gas station several times in a row and get different qualitity gas each time.

A DTC 301 set at high (over 4,000) RPM with no other obvious faults (i.e., good: plugs, wires, coils, ignition control module, fuel pressure, etc) may suggest a faulty PCM (powertrain control module). It appears that GM had a problem with PCM's for Bonnevilles that year. Incidentally, GM warrants PCM's for 8 years/80K miles. Does anyone have any insight into DTC 304 alternating with DTC 401 for a 1998 Bonneville VIN K - not supercharged)? All of the usual suspects (coils, module, plugs, wires, etc) check-out fine. The problem is intermittent, occurring without a predicatble pattern. Runs fine for awhile, then check engine light and occasionally flashing check engine light. No obvious harness problems visible. Dealership is totally useless with this one: car has 60K and terrific maintenance history. Help?

This can be a challenging code to troubleshoot. My experience has lead to different conclusions. Like above, I have seen worn plugs, bad wires bad coil packs, bad ignition modules, bad ECMs, bad fuel injectors. Rarley a bad headgasket. The most common ones seem to be on the 3.1 engines. Take it to an independent repair shop and try a fuel injection cleaning. the fuel additives won't resolve it as they remove the waxes, but don't really clean the injectors. A professional cleaning involves disconnecting the fule pump and running the motor on this cleaner. I have seen it resolve PO300 codes, make cars run incredibly better or also do nothing.

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Ford Ranger
Check Engine Light
VW Jetta

How do you reset the 'Check Engine' light on a 2001 Ford Ranger?

Disconnect the battery cables for 15 minutes. Then put the key in the ignition and turn it as if to start the motor, and hold it in that position for 30 seconds. (This resets the computer, codes, engine, everything.)

When powering it back up and running the engine, it may run slightly rough for the first few minutes as the motor resets and re-samples all systems.

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Auto Parts and Repairs
Check Engine Light
Grand Am GT
Grand Am SE

Why would a 1999 Pontiac Grand Am Service Vehicle Soon light come?

I have had the light come on when I had a headlight out. me too. 9/15/05

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Chevy Silverado
Check Engine Light
Nissan Sentra
1995-2005 Chevy Cavaliers

If the 'service engine soon' light comes on in your used 2001 Sentra SE with 81K miles on it is this serious?

It means take the car to the dealer for its scheduled maintenance.

You can also check for a reset button for your vehicle. In a certain number of miles the check engine light will come on you you can take it to the dealer and they can charge you $50 to $100 dollars to reset it. They won't tell you your vehicle has a reset button they will tell you to bring it in.

its probably just the oxygen sensor. have it looked at/ its not that serious

Mine came on at 105K kms (~ 65K miles). I bought an OBD II Code reader off of Ebay for $50 and found out that the 'System was too lean' So it's not serious in my case. But I haven't taken any steps to fix it. A friend recommends I take care of it since a lean system can cause wear to the valves.

Mine came on at roughly 80k, the engine would stall while I was breaking, and excelleration became difficult. I had the code read and it was I believe bank 1 sensor 2...system too lean. I had it diagnosed and its the mass airflow sensor. You can take this part out and have it cleaned or you can spend the 500-600 on the part from Nissan (not including labor time) because they insist the car will chew up and spit out generic brand sensors (nissans are nitorious for it ANYWAY!)

A code reader for your car is a pretty good investment. Two or three uses will generally pay for it. If your code indicated something like a defective oxygen sensor or a mass air flow sensor, you would probably want to get that fixed because most of the errors you see will affect gas mileage and at todays prices, can you afford to ignore it?

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Dashboard Lights and Gauges
Check Engine Light
Nissan Pathfinder
How To

How to fix it check engine light code P0455?

P0455 means a gross leak detected in the Evaporative Emissions System. Some call this a "gas cap" code, because the most common cause a loose or failed gas cap. But it could be caused by any vapor leak in the fuel tank, filler neck, or anywhere else in the vapor management system. If it isn't a gas cap, you will need tol take it someplace where they have a smoke machine that can find the leak using smoke.

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