I'm getting a couple of O2 sensor codes, I forget the numbers, but both are B1S2 (rear sensor). One says the readings are bupkis, yeah, whatever, and the other says the heater failed. The catalytic converter is good because I replaced it with a nice Magnaflow (not the high-flow, and not a dinky one) and I know it's working well. (I replaced it 'cause my stock one was so clogged, the engine wouldn't stay running.) The truck runs nicely, just that I get those codes that prevent me from passing inspection.

Thing is.... I'm getting < 1v on the harness side on the heater wires with my DMM (which I know works because I use it quite often on various projects that I do). I don't understand it. I'm reading it with the O2 sensor disconnected, so it's not a short. I've tried it with the circuit open and also with a 20ohm 20W resistor (reading across the resistor) and with the resistor I don't get any voltage reading at all. I want to point at a fuse or something, but I don't know. Weird that I'd get voltage with it open I think.

Any ideas?

 

Ive had the same problem for about 6 months or so.. maybe longer, ihave tried EVERYTHING to my knowledge to get it fixed.

Reroute a wire and bypass,
New O2 Sensor
Check for shorts
Unplug it
check pcm connections
ect..

only thing i have not tired is replassing the engine harness.. honestly i think on MY truck my harness is screwed.. and not sure why. But thats just be im getting alot more codes then just heater... but ya.

I would try unplugging the 02 sensor and ziptie-ing it to your frame rail. and reset the computer.. it might let it the CEL Turn off.. give it a try.

 

That sucker doesn't want to come out. I build an O2 simulator for it. I know the cat. is working anyway and I had all the parts, so screw paying for an O2 sensor, I said. Thing is, even if I get the sensor to read that the exhaust is clean, the heater problem will still fail me for emissions.