Check Engine Light

The 'oxygen sensor'may need to be replaced on '96 Sentra when the check engine light comes on. The should be replaced on the '96 Sentra every 100k miles for better fuel efficiency and to protect the converter.

Because you did not have a faulty EGR valve. You misdiagnosed the problem. Start over and remember the code only tells you what part is being effected not necessarily the defective part. This is assuming you reset the light or drove the car enough cycles for the light to reset. If not then reset the light and see if it comes back on.

its actually code 12 which means that the battery or computer has been disconnected within the last 50 cranks

What engine light. Check engine light means there is a problem that is effecting emissions. Oil light means low oil pressure. Temp means running hot. Maintenance light means maintenance is required, like changing the oil. Owner's manual lists all of these. 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

You need to have the ECU scanned with an OBD2 scanner and retrieve the code that has been set. The code will tell you what part of the emissions system is being effected. This will help you diagnose the problem. Or you can keep spending money throwing parts at the problem until you may or may not find the faulty part.

The check engine light (service engine soon) comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. 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 a parts store 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.

The check engine light (service engine soon) comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. 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 a parts store 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.

On any car with an engine light on, go to an auto parts store and have them scan the trouble codes and either fix whatever the problem is that's illuminating the light, or have the person reading the codes to erase them using the scanner.

You can reset the light by disconnecting the battery for 10 minutes. It will come back on again if you do not correct the problem that set the light in the first place.

1. Turn off the engine.

2. Press and hold the select and reset buttons on the instrument panel, then turn the ignition switch ON (II)

3. Hold the buttons for approx. ten seconds until the indicator resets.

Remove the four instrument panel screws. On an automatic transmission model you must also remove 2 screws and detach the gearshift indicator cluster. When you pull it out partially.. disconect the speedometer cable from the back. Once you have it out you will see all of the instrument bulbs on the back. Please disconnect your battery anytime your working around or near your airbag system.

Turn the key from off to on, the quickly off on off on off on the codes should show up in odometer spot

You can't manually get the check engine light to give you the trouble codes on your vehicle. 1995 and later vehicles use the OBDII system and you must use a scanner tool to retrieve the codes. You can go to AutoZone or similar auto parts store that offers free scans to get the trouble codes retrieved. Or you can buy your own scan tool for about $70.

The Engine is still there, I assure you, When the light flashes, it means there is a condition present that is damaging to the Catalytic converter. Too much raw fuel is getting through to the converter, from a likely MIS-FIRE. The Engine has a MISS (mis-fire). A mis-fire is that the fuel is not getting burned for what ever reason- bad wire, bad plug, low compression, too much fuel entering the combustion chambers, etc. 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

Have it scanned and fix the problem, or have it scanned and delete the fault code. If you choose just to delete it there is no garuantee that it will stay off.

Hard to say without more information but my educated guess would be you have a vacuum leak on this 13 year old car. Inspect all under hood vacuum hoses. A scan of the ECU with an OBD2 scan tool will tell you more.

Yes, it will. Your engine will not run properly without a converter installed. It is also illegal to remove a converter and carries a $2,500 fine if you are caught.

Must have damaged a spark plug or mixed up the firing order during replacement. Check the code(s) and you may find a P0300 thru P0308 which will help determine what cylinder is misfiring.

Disconnect the battery for 24 hours. A pain? Yes, but mine comes back on within a few hundred miles. I need to change the pricey 02 sensor. That's a letter o not a zero.

March 2008

My check engine light came on during this past winter....I knew I had to do some work on the exhaust system. Turned out that I needed new flex pipe after I had that replaced which was only a little over $100 the light went off and hasn't been back on.

Update: May 2009 Check engine light has come back on now...guess my oxygen sensor went bad...car's been acting funny lately, overheating in idle and whatnot. Hoping that a new sensor will fix this issue.

intermittent OBD code fault. typically EGR fault will cause light to flash as valve opens and closes continually in reponse to changing throttle position and vehicle speed.

It could.

It could.

There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.

you are low in oil and you need a service

Have vehicle scanned to determine problem and have codes cleared