As most of you know, tracking down wiring issues can be a PITA. I bought my son a 2002 Mustang GT with some mods to include LT headers, a hi flow catted SLP exhaust and some other goodies. The problem is that the damn rear O2s and heater circuits had many codes. Replacing them didn’t fix it nor did eliminators. Eliminators still require working O2s. So I knew the problem lay in the wiring. Neither the installer nor a separate shop was able to fix the problem. They kept blaming the long tubes or the hi flows. Wouldn’t even listen to reason when I explained why this wouldn’t be the case. Finally, I traced the wiring harness and found the O2 harness wires were crunched under what looks like the trans mount. Upon inspection I saw tons of copper peeking out. 6 of the 8 wires were cut. Once I fixed the wires the problem was gone and after some driving was able to pass inspection. Thank god and thanks to some of the other members who posted solid info on how to check the wiring on these pigs- Clampett5 out
This is good feed back. It might help others more if you posted the DTC codes that were seen. Sometimes the combination of DTC codes along with wiring diagrams can give a clue. For example. All four of the O2 sensors heaters are on the same circuit. So it would follow that a ground fault in one of the O2 heater circuits would blow the F2.8 fuse. It would also follow that all four O2 sensors would also throw DTC codes due to a lack of power.
Sometimes the devil is in the small details.
I know that many people that post on the forums don't think that they can find electrical problems. Sometimes seeing someone else's success story can be enough to inspire others.
The code at the time of my trouble were P0136, P0141, P0156 and P0158. I had some other error earlier but I forget the code. Turned out my vacuum line from the TPS was collapsing. Replaced it and whatever that code was went away