A day or two after I installed my CAI, my 'service engine soon' light came on!

I've tried resetting the ECU by disconnecting the battery overnight, but after a day it came back on!

Does anyone know what could be wrong, and how to fix it?

I've tried reading the ECU code but my car is a '99 and that black ECU box is different than the other 4th gens'. It requires a small philips I think and it is in such an inaccessible location I don't think I can reach it w/out calling a mechanic to do it.

Anyways, if I just leave the CEL on for a few days, will it eventually go away as the ECU somehow becomes adjusted to the cold air?

My car is a '99 and has ~25k miles so I don't think the o2 sensors could be bad.

Ahh I am so frustated, especially since I spent all that time installing the CAI in the first place. It would be such a shame for me to have to return it to stock!

All help will be greatly appreciated!!!

 

Maybe the ambient air sensor, the MAF, a hose, something you forgot to hook back up?? The ECU is silver, and its right under the center dash, after you pull off the black plastic which hides it.

I wish I knew more about the 99s. But there is no distinction between the ECU's noted in my Haynes Manual, so you may be looking in the wrong spot.

 

I see the ECU unit, and it looks the same as the ECU writeups that I have read--but it says "Idle Adjuster" on it instead. Also, there is no screw inside for me to turn!