SOMETIMES my check engine light comes on while I'm driving. It only comes on after the motor has had time to warm. I would check my computer for the code, butafter my car turns off, the check light goes away!

If my car is warm AND the check light is on AND I just REstarted the car, the check light will not be there but will return in a couple minutes.

How does it drive? Fine as can be...

Do these symptoms ring any bells?

 

o2 sensor maybe

 

^Was thinking that because its only when warm.

Though IIRC the aux ports solenoid is also only activated when the car is at running temp, though the aux port soelnoid also won't trip the CEL light.

Check the codes and get back to us...
s4 - http://www.1300cc.com/howto/how2/codes88.html
s5 - http://www.1300cc.com/howto/how2/codes.html

 

does your car go to limp mode in the process?

 

My car does the same thing. It's my 02 sensor.

 

i knew it!!!

 

Check the TPS also for blow opens or zeroing throughout the travel. I had a similar problem when I first got my car and the TPS was the culprit. It would only happen at certain throttle positions at certain rpm's. weird stuff. Besides, replace the o2 sensor anyway. Cheap insurance.

 

Cool. Does anybody have another O2 sensor?

 

Any auto store will have it. Just a regulary bosh type o2 sensor with a specific thread pitch. Tell them the make and model and they'll get it to you. I think they cost around $20-$40 depending on what quality(brand name) you get, they are usually all OEM, so it doesn't matter too much. I just get the cheapest, if I wanted an accurate a/f ration, I'd get a wideband.