Check Engine light - on and off

[JeffGoTerps]

My Check Engine light has been coming on randomly for the past 2 weeks. It only comes on when I start the car, and does so about half the time. If it turns on it's there for the entire trip, and sometimes clears the next time I start up. Autozone says they can't read the code if the light is off. Are there other places that can? Should I even worry about it if it's not consistant?

My gas mileage is still normal (28 MPG highway). I've had the gas cap problem before, and I'm sure it's not that.

[rckrzy1]

autozone does not hire some of the smartest people. The code will store usually for 3 cycles or about 100 miles.

[rixGAphx]

If the light is 'off' because you disconnected the battery, then codes can not be read since the 'disconnect' (for 10+ mins) essentially erases the codes stored in memory of the PSM (engine 'puter).
This is prolly what the AZ guy was thinking.

If the light goes off by itself, then you have an intermittent problem, and the PCM is designed specifically to keep these codes stored for a long time (more like 32 or 48 engine on/off 'cycles', IIRC, for a '96).

Chances are quite good that the code will be related to O2 sensor, catalytic converter efficiency, or P0300 (multiple/random misfire).

When the respective part is beginning to fail, these codes come along, then disappear after one or 2 cycles of 'proper operation'.

Go ahead and read the codes, and report back.

Good luck.
-Rick

In your many future (hopefully enjoyable) years of working on cars, this Old Guy recommends you NEVER rely on the theory,
'It can't be that, I just replaced it.' :eek: :D :D

[JeffGoTerps]

My fault here. It's actually the "SERVICE VEHICLE SOON" light, not the "SERVICE ENGINE SOON" light. I didn't realize there was 2 different lights. In the manual it says it may be related to day time running lights. Looking back now, the "randomness" was dependant on the time of day I started the car - it only comes on during the day when the daytime lights are supposed to work. And I took a look at my lights - one is burnt out.

Found this out after driving all the way to Autozone for lunch today and getting a "clear" read. I read the manual on the drive back - sure beats paying attention to the road.

[rixGAphx]

Great for you!!

Just a note: the DLR system is supposed to work 24/7. It's supposed to change from DLR's to regular beams when the ambient light is low enough to indicate evening/night.

-Rick

[RocketFast321]

also you could have a bad tail light bulb or head light.