1996 Jeep Cherokee Sport 4wd 4.0litre 113,00 miles.

About ten months I had my mechanic install two new o2 sensors I got from the dealership and a new catalytic converter. My mechanic installed the parts for me and had to fix a bad ground wire for the heater circuits on the sensors. Once that was fixed they worked fine and I haven't had a check engine light come on till about ten months later, it is saying that both heater circuits are out and I have a high voltage on the oxygen sensor behind the cat. I was looking at a wiring diagram for the heater circuit and noticed that they might be controlled by a relay but I can't find the relay anywhere on the truck. Does anyone have any experience with this? It just seems odd for both circuits to go out on sensors that are less than a year old. anyone have any suggestions on how to trouble shoot this problem. Thanks for your time

Kevbob

 

i'm betting on a wiring short issue. Check the wires going from the pcm to the sensors. They pass pretty close to the exhaust manifold and have been known to melt at that spot if they get close enough. If multiple wires have melted and are shorting out that would be the cause of your issue.

 

Ive also heard that there is a fuse somewhere in the fuse block.. I can nver remember which one.. Ima look around to find it, but im sure someone else will know.