So my ses light went on, it was p0138. O2 sensor high voltage, I remove the batt cable, maybe get rid of the light. Well at first perfect no light car runs great. Then 4 miles down highway I stop at a light rough idle. Im don't sure how a pc reset would cause this any help? My car is 04 Evo w header turbo back exhaust stock blow off and everything else stock running 12 lbs boost

 

Ok so I drove a little further, now ses light back on and still bad idle

 

Sure sounds like a bad rear O2 sensor, my 8 seems to eat those, I'm rocking a p0138/p0141 combo right now. I think the test doesn't throw a code right away after clearing, only after a few min driving. I've never had a stock tune, so I don't know for sure, but maybe the stock program relies on that O2 signal for adjusting the maps, and now it's running pig rich to save the cat?

I say get a new sensor, or get a tune that removes the rear sensor test altogether, g'luck.

 

That sounds good to me is there a way to test them befor buying a new one the bosh one is like 200 I think a denso is like 140