I have a 1998 Cherokee that I just bought. 30 miles after buying it, the check engine light came on. Put my scanner on it and the codes were for the o2 sensors. I replaced both sensors and the check engine light came back on with same codes. I did find some frayed wires on the bank one sensor harness. I fixed that, turned the light off again and same thing. Light back on, same codes. Meanwhile the jeep would have a bad hesitation for the first fiveinutes of driving. After replacing o2 sensors, plugs, wires, distributor cap, catalytic converter, the fix was a $2 part. In the fuse panel under the hood there is a 15 amp fuse that runs the o2 sensors. It was blown. Now my jeep is running perfect. No light, no hesitation and the gas milage has improved by 3 mpg. By the way it's a 4.0, automatic, 4x4. Hope this can help someone else out. I know this is a pretty common problem.

 

It might seem like common sense but most of us are just like you. We find out what the trouble code is and we go right to turning a wrench. It is a good thought process to check your fuses first.

 

That fuse controls the "heater circuit" of the oxygen sensors. And yes, it is often overlooked when troubleshooting oxygen sensor codes. Don't feel bad...........

 

this post helped me out with the o2 sensors, and your saying the o2 sensor fuse is the same for my heat. well my heat doesnt work i changed the blue 15 fuse to a new one and still no heat, any ideas?

 

I'm having the exact same problem as the OP had above and I never would have thought to look at the fuse first. Thank you very much for posting this advice. I don't know if that's my problem or not just yet, but it's a great place to start. Thanks again!

 

The oxygen sensor fuse is for the HEATER portion of the oxygen sensor. It doesn't have anything to do with cab heat. That is a cooling system issue.
Thermostat, cap, heater core, etc.

I recommend starting a new thread for this symptom. Give plenty of detail.

 

OK, 3 sets of 02's cap rotor plugs plug wires and I read this and sure as hell.....blown fuse. i replaced the blown 15a fuse and I guess we'll see.