Thread: SES light after installing reprogrammed PCM

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!

If your nor running a catalytic converter is will throw a code for an o2 senor. On an obd2 car there are at least two o2 sensors. one before and after the cat. So if your not running a cat that last o2 sensor will be reading incorrectly causing a checkengine light

Thanks guys. I don't have an other injector of MAF mods. Have a cold air intake system going to the fender, a downpipe, and 3.4 Pulley. I did have a mechanic tell me my fuel pump was getting weak, ut didn't have a problem with old PCM....?

Also, where is the front O2 sensor located? Could he have taken out my CAT and both sensors...then programmed the PCM not to read either (just replaced both O2 sensors about six months ago....he down pipe and removed CAT about three months ago)?