While off roading I got high centered and disconnected the lower O2 sensor and lost the plastic connector on the harness end. Unsure what wire went where into the O2 connector I guessed. My check engine light stayed on even after reseting the ECU. Yesterday I found the right match for the four wires and connected it correctly. Now my Jeep loses power, almost like it's running out of gas, for the first 3 or so min until the engine warms up. When the engine warms up it runs fine. I found a blown 15 amp fuse under the hood and replaced it, but this did not help. Could the O2 sensor itself be damaged, any ideas??????? This has been going on for a while and I would really like to get to the bottom of it. Oh, and after I connected it correctly yesterday, I reset the ECU and the check engine light went off and has not come back on. I'm stumped. It's almost like the XJ runs better when the check engine light is off. Thanks.

 

Sounds to me like you are on the right track.

Your sure the 02 sensor is wired correct, you replaced the 15 amp fuse (smallest of the fuses, back row 2nd from the passenger side)

Check engine light stays off.

Now disconnect the negative battery terminal for one minute to reset the computer & it should run right after a mile or two.

 

Here are some pics of the fuse box under the hood. The fuse that I am pointing to with the pen is the one that was blown and I replaced. Is that the right one?

 

Just in case the angle is confusing, the right side of the pic is toward the front of the Jeep, the left side of the pic is close to the firewall, the top of the pic is towards the inside of the engine bay, the bottom of the pic is close to the passenger side fender.

 

Bump. Short update. Left for work this morning and the XJ did the stalling thing for the first few min then ran great. Still no CE light.

 

bump

 

bump again.

 

Bumped again. Anyone???

 

Bumpity bump bump

 

Sorry man, I was working today. I've been going back through the posts, & this was on page 4.

That is the fuse that fixed my problem with the C/E light & the O2 circuit/heater code.

Mind if I save & use your pic to help others?

Also see that it's running right now, did you disco one of the battery terminals?

If not, the computer may have learned this got fixed by itself.

 

You can do whatever you like with the pics. Even after replacing the fuse the Jeep still runs like crap for the first few min until it warms up. My check engine light stayed off until this morning. When I left for work this morning the CE light came on and the Jeep ran fine. So, I'm wondering if 1) My O2 sensor is wired wrong or 2) if the O2 sensor is shot. I just don't understand why when the CE light is on the hesitation and loss of power prior to warm up goes away!!!!

 

i been told wired sensors never work

 

Try pulling the code, see what it tells ya.

Im guessing the o2 is bad.

 

I'm guessing it's bad too. I just don't know why it doesn't run bad when the CE light is on. I'm gonna check the codes soon.

 

IIRC, the rear o2 is only to monitor the cat. If its sending a flase signal to the ECU it would trigger a CEL. The cat may be clogged as well. PM'd you the way to check the cat.