The "Service engine soon" light has been on in the 2000 Oldsmobile Alero GLS coupe for a couple of months. Drove me nutz. Finally broke down at took it too the stealership. It had a small air leak at the gas cap. So after paying for the dianostic, and gas cap, the light is out !!!!!!! The original cap broke, and I bought a replacement gas cap from NAPA. It never did fit right, and the stealership said it wasn't the right cap for this car. Why am I not suprised CRAPA gave me the wrong part ?? I swear, I honestly believe giving the wrong part(s) is standard opperating procedure at CRAPA !!!