A little backstory this is actually not my Jeep but a very close friends. I am a seasoned mechanic with 13 years of experience. He brought me the vehicle after replacing all four O2 sensors. Replacing the PCM with a Wranglerfix PCM and getting to his own wit's end with it. I started by pinning out and checking resistance and continuity on the O2 wires and not just the heater circuit. Everything was checking out but I still went ahead and replaced the g104 ground. I then turned to the O2 sensors and replaced all four of them myself with ntk sensors. When that didn't work I decided to load test every wire in the O2 system and everything still checked out. What I am seeing is a maximum voltage of 4 volts being supplied from the PCM to the O2 heater circuits. I called Wrangler fix and spoke with Jay and he was very insistent that it was some sort of wiring issue. Me at this point throwing parts at it decided to try a Tipm as I know there the center of all power distribution on these vehicles. Still nothing. I am at a loss and I no longer know what to do. I've tried everything from overlays to load testing and it just really seems like a PCM issue to me. Has anyone else ran into this?