Hi guys! Just found this forum over the weekend while searching for some help, so I figured I should join. I have a 1998 GMC 2500 3/4 w/ 7.4l (will get pics up soon). Last week I got a check engine light and borrowed a code reader to see whats up. Ended up with 2 codes: P0141 - O2 sensor heater cicuit malfunction bank 1 sensor 2; P1415 manufacturer control auxillary emission control. After resetting the faults, only he P1415 keeps coming back. It's for the air pump, or smog pump as some call it. Everything appears to be working normally, it comes on when the engine is cold and kicks out after a short while. The diverter valve also looks good according to the Haynes manual test procedure. Somehow, I don't think that the pump is the reason for the faults, maybe a bad O2 sensor - emmisions related problems are hard to diagnose from my past experience. Anyways, if somebody has some past experience with this or any clues, I would appreciate it since I need to pass DEQ by the end of the month. Thanks alot.