service engine light going on and off

The "check engine" light is an indicator for a system that monitors many electronic functions in the system, also called the "malfunction indicator lamp" (MIL). It can come on for any of hundreds of different causes from any of the systems that the computer monitors. Some are very important and can lead to further component or engine damage and some are emissions related not as serious but still a problem and need to be repaired.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 1995 cars. If you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be.

Hello SIERRA GUY,

If you decide you would like to conduct the scan yourself here is a link to an article that features written step by step instructions and pictures explaining how to do the scan yourself, also I have included a link to our YouTube channel with a how to video on code scanning.

This is applicable even if your check engine light is not on.

Most scanners are inexpensive to purchase, you can purchase one online from sites like Amazon.com

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://youtu.be/YV3TRZwer8k

Once you have the codes please get back to us so that we can further assist you. We are always happy to help.

Thank you for visiting 2CarPros.com.

Kindest regards,

Renee
Admin

here's the codes I got from autozone
P0171 bank1, P0174 bank2

That indicates you have a lean condition. You need to look for things like vacuum leaks, leaks in the intake snorkel, low fuel pressure or bad Mass Air Flow sensor.

I'll clean MAF sensor. I know not to touch the wires in sensor.

Thanks

You can try that but unless you have been using one of those oily K&N filter, it not real likely to be the problem.

Turns out after having a mechanic check all the possibility's, it was the MAF sensor.
by the way I don't use one of those oily K&N filters.

In that case I suspect cleaning didn't help. Glad you found the problem anyway.

Cleaned MAF sensor again, reset codes and everything seems to be fine now. Even getting better gas mileage.

Thanks again for your advice,
Tom

Cleaned it again? I thought you said you replaced it.