Ferocity02

iTrader: (60)

I just put my truck back to stock other than a 4L80E instead of the 4L60E. I put in brand new Bosch rear O2 sensors. I'm getting codes P0140 and P0160 for no activity for the rear O2 sensors. When I log with EFILive, these sensors are flatlined at ~450 mV +/- 5 mV... no real activity whatsoever. It's basically like the sensors are unplugged.... I unplugged a front sensor and it also shows ~450 mV.

I bought another O2 sensor, same thing. The heaters in the sensors work great. I bench tested one sensor and I think it's working fine, responds to fresh air vs. gasoline-rich air.

I did continuity tests on the tan and purple signal wires that go to the PCM and they are fine and do not appear to be shorted to any other wires going to the PCM or ground. The wires are physically in tact, no melting or anything of that sort.

I am using a stock tune flashed into the PCM with nothing but a 4L80E trans segment that has been modified slightly for gearing. The engine calibrations are all stock other than a handful of transmission related DTC enablers that were changed. The DTC enablers for the rear O2 sensors are all stock... "2 trips, emissions related."

Anyone have any ideas? I am at a total loss here.

Ferocity02

iTrader: (60)

Anyone have any thoughts? Still scratching my head on this one. I flashed in a 100% stock tune and no change.

musthaveLSx

Rear sensors do not toggle.
They are used to determine if the cats are functioning correctly.
I can't give you a definite level, but 2.5V seems correct. It's something you will have to research further.

musthaveLSx

I just spoke to a calibrator, and 450 to 550 mv is correct. So .45 to .55 volts flat output. If the cats are gutted, then they would toggle as the fronts do.

musthaveLSx

http://www.obd-codes.com/p0160

Ferocity02

iTrader: (60)

Turns out the 2 O2 sensors I got on eBay were bad. Figures.

The 3rd one I got locally works fine, when I tested it at first I was not grounding it properly.