90quattroman

So I was getting DTC p0154 (no activity on O2 sensor bank 2, sensor 1) and since the car is at 102k, I figured it's probably time to swap it out for a new one. Just to be sure, I cleared the codes, made sure the sensor harness was plugged in tight and took it for a drive. Sure enough, the second time I started the engine and drove for about 5 minutes, the same code somes back. So naturally, I swapped out the drivers pre-cat O2 sensor and cleared the codes again. Drove for about 30 minutes and all was fine. Today I start the car up and the CEL is back on and the same code is back, plus a new one this time P1131, which according to the audi code bank means "internal resistance too high" for the same sensor. What gives? If I'm speculating correctly, there must be a wiring problem, maybe from the sensor lead plug to the ecu? Any thoughts? It actually looked like the leads from the ecu had been cut and spliced before on this car, since the leads were too short to be mounted on the firewall in the harness clip, and it was wrapped with electrical tape. but I inspected underneath the tape and I couldn't find a splice or anything. Any help is appreciated, since my temporary registration is up soon and I need to pass inspection.

90quattroman

Soooo . . . anybody got any ideas?

complacentsee

I would keep looking for a wiring issue and take a log or 2 if you can.

RolledMySTi

Do you have a bentley manual? I'm sure there is a way to test the volts going to the sensor to see if there is a problem with the wiring.

90quattroman

That was my next move, but haven't received my DVD yet. If anyone has a wiring diagram or something, it would be appreciated in the mean time. Thanks man.