GregCon

Well, after some messing around I fixed the issue so I thought I would post the fix here as a follow up.

The car was showing a P0154 code which is no activity on the Bank 2 Sensor 1.

I used the scanner to watch the STFT and O2 sensor voltage for the Bank 2 Sensor 1 O2 sensor and in general the numbers were not what they should be...in fact they were either 0 or barely above it for the voltage, and there was a lot of STFT correction going on which meant the computer was trying to richen up the mixture to compensate for no inputs from the O2 sensor.

I replaced the sensor with a new Denso unit and the readings were good for a few miles, but then they degraded quickly and the CEL and VSC lights came back.

I started looking at the wiring harness, where the O2 sensor plugs in, and it looked perfect. It was not something I disconnected during the plug/valve cover gasket change, either. But then I pulled on each of the 4 wires and one came right out of the connector. I pulled the terminal out, and you could see where it had been over-crimped when new. In fact, it looked like it spent the past 8 years and 121,000 miles working by proximity contact only. I am sure the work I did caused the harness to move a little which was just enough to move the wire out of contact.

So, I soldered the terminal box on to the wire (you can't recrimp this type of terminal) and it works great now. No more lights.

The connector/terminal arrangement is really dainty for an underhood part, IMO. If it ever gives trouble again I will replace the entire 4 pin connector with a 4 pin GM-style Weatherpak connector which uses a mechanically stronger terminal and is easy to buy. But for now it is working well and I doubt it will break again.

kayuwong

DuckyB

I had the same issue and code. After replacing Bank 2 Senor 1 with no cure I took to the dealer . Banks 1 & 2 Downstream sensors and ECU are bad. very expensive repair, if taken to a Dealer

kayuwong

kayuwong