Just got my car done wich is a turbo k20 6766 4" exhaust. I have two brand new O2's on the car. A PLX and a new OEM wideband. They are both placed about 2' away from the turbo and after a bend, and there is still another 3' of pipe after the sensors. They do not read the same. The PLX is about an entire point higher then the OEM that's reading throught the ecu. Basically the PLX says 14.4-14.5 while the OEM sensor is reading 13.5. Car is on E85. Wich one should I trust?

 

Grab a known good third sensor, and start tuning. It will become apparent which one is "correct" when you start making fueling changes with a dyno.

 

Did you calibrate both sensors when doing the change?