I have a similar problem with my 01 GTP. I swapped out my PCM for a reprogrammed PCM from 3800 performance two days ago. After driving it for about two minutes, the SES light came on. So, I took it to the dealer the next day to get the CASE learn done (was told that should clear the SES light. Two minutes after I leave there, the SES Light comes back on. So I took it to Autozone and got it scanned...came up wit a P0171 (aaFuel trim bak one condition) code, and a P0137 (aaH02S12 circuit condition (heated oxygen sensor bank aa1 sensor 2) code. Disconnected the battery for ten minutes, reconnected, the light was out. Was driving this morning for ten minutes, then the light came back on. Went back to Autozone, had the P0171 code again (and maybe the P0137 code too, but he said there was two 171 codes, and cleared them for me before I could confirm if the second code was in fact the 137 code). Drove for five minutes, then the SES light came back on. One thing I must mention is that I have no CAT on the car (didn't have one with the old PCM, but buddy of mine may have tweeked the last PCM when he put in down pipe with no CAT). Could the problem be my O2 sensor(s), or no CAT and reprogrammed PCM picking that up? Please help!
