DTC codes P0156 & P0161 on bank 2 sensor 2

[vvansant]

Hey gang, long time no chat!

I've been fighting a pesky O2 problem on my 96 Mustang GT for a few months now, it keeps throwing P0156 & P0161 on bank 2 sensor 2.

This started last fall with the original stock exhaust. The so-called "experts" at my local muffler shop plugged in and said I needed a new mid-pipe because my cats were bad. I said thanks, but I'm not interested in putting a replacement stock pipe in for $1200. Instead, I bought and installed an after market X-pipe with cats. I love the performance and sound of the new pipe, but my computer was still throwing the same codes after about 15 miles of drive time.

Next, I put a new O2 sensor in bank 2 sensor two, same thing. At last count, I've been through 4 different sensors just to make sure. I had a performance shop check it out and they said it was either an exhaust leak or a bad sensor but when I took it in they couldn't find a leak. The only thing left that I can think of would be a short in the wiring harness somewhere or my PCM has gone nuts, but I'm curious to see what you guys think. If I'm right about the short, how on earth am I supposed to track that down? Any suggestions would be appreciated, thanks!
--
Vince

:SNSign:

 

[Dragstr05]

What would really help narrow this down real fast is the code description. There in reality are several codes for that single O2, some for the sensor and some that are geared toward the circuit itself.

If you have access to a scan tool, it wouldnt hurt just to look at the data list to see if the PCM is actually getting a signal from the O2...that would rule out the short.

You stated nothing about having MILs. This itself could be your problem. Even my catted bassani x threw O2 codes. If you dont already have them, get some MIL's, plug them in and go - your issue should go away.

 

[Mike97gt]

Those are circuit faults, I have no idea how the first shop came to the conclusion that
you needed a midpipe. Also I have no idea how the second shop thinks you have a exhaust leak. This really leads me to question the ability of those shops.

You need to check the wiring harness and connector that runs up to the pcm. You probably have some corroded or broken wires in the harness or a damaged connector.

Now if you had cat inefficiency codes then I could see how they came to the conclusions they came too.

 

[vvansant]

I forgot to mention that I am using inline MIL eliminators also.

Yes, I also have lost confidence in many of my local fix it shops. I think their just out to make a buck! Thanks for the tips, the connectors look okay but who knows...I like the suggestion about wiring up to the PCM. I'm not sure how to trace that b/c doesn't it disappear for a time into the chassis?

 

[Mike97gt]

well you can check for continuity from the pcm to the sensor itself. One thing to watch out in this type of test is that if a strand or two is ok in the wire then it will show up fine in a continuity test but when the wire will not be able to carry the load needed for the circuit to work properly.

 

[vvansant]

I assume the PCM is located under the dash somewhere right? If I'm not mistaken, it is the bluish colored box that sits under the radio head unit. I've seen other references point to a PCM located on the other side of the passenger compartment behind the kick panel.

Out of curiousity, has anyone here ever used the "OBD-2 Vehicle Explorer Scan Tool Browser" by Alex Peper (aka Car Code)? It seems like a really good diagnostic software but I struggle to understand what all of the various parameters represent.

By the way, the description of those codes is as follows:

P0156 O2 Sensor Circuit Malfunction (Bank 2 Sensor 2)
P0161 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)

Thanks!
--
Vince
:SNSign: