I started by inspecting the harness and wires which had been rubbing on the drive shaft. I repaired the wiring and the codes stayed away for roughly 200miles before coming back. I got a new ntk sensor and replaced the downstream sensor as the sensor had taken some damage before my initial inspection. Codes went away for a while before coming back. I just finished inspecting and repairing more frayed working on the male connection side wires to the jeep itself. I have yet to clear the codes and see if it's fixed but while I had the vehicle running, checking power, I noticed some water sputtering out of the exhaust. I wanted to see what you guys thought about that and if it could have anything to do with the codes I'm experiencing. Thanks!

Edit: P0138 came back on after a short drive

 

That's just your standard condensation from moist exhaust and cold muffler.

 

agree

 

Water from the exhaust is normal condensation, not your issue. Since P0138 keeps returning after repairs, the problem likely runs deeper than the wires you've fixed. The constant rubbing probably damaged wires further up the harness you haven't found yet, or possibly even damaged the ECU's driver circuit for that heater code (P0141). You need to check continuity on every single wire from the ECU connector all the way to the sensor plug. The fix is almost always more broken wiring.

 

Thank you. I found more exposed wiring further up, removed and spliced back together. Codes came back. I just visited the junk yard today with no luck seems like the exhausts are some of the first parts to go on these vehicles. My plan is to keep looking and try to replace as much wiring as possible from the male end. How would I check continuity in each of the four wires?

 

Multimeter is your friend. Even a cheap, one will become your best friend for doing electrical work