My 96 XJ doesn't have a downstream plugged in. The PO either pulled out the wires for the sensor or they got caught on something and pulled out. Anyway today I cleared the codes because I finally got to the junk yard and pulled a pigtail and sensor from where the PO cut the old one off for the battery sensor. When I cleared the codes the CEL never came back on like I expected it too. I know one of the previous codes was the downstream o2 sensor. I drove it for about 20 miles and have done several shut off and starts in the driveway. Just curious if this kind of a normal thing once the code is cleared that it takes a while to come back on. I figured it would throw the code immediately or at least after everything warmed up. Should I be worried about something else screwed up now?

 

There was an ECU software upgrade for '96 to fix that specific problem- the CEL wouldn't always turn on when the rear O2 detected a failed cat. They usually did that upgrade when you brought it in for the failed cat. (another '96 problem- first replacement is free)
Could be you haven't driven enough too.

 

Are you sure the CEL bulb is there? If someone removed the O2 sensor, they may have removed the light bulb to make it go away.

 

Yes it does. It didn't when I bought it though. That was one of many surprises I have ran into with this Jeep. I think the PO had a lot of aftermarket stuff on this XJ and instead of running power correctly he would just reroute power from existing things he didn't want to run and just pulled the bulb for the CEL. So thats been fun let me tell you. Everytime I go to do anything I usually run into wiring issues.

Anyway, light came back on first thing after I made this post last night. All the codes are related to that sensor. Going to order the sensor today since I got my tax return I set aside a bit for doing some necessary repairs. Just hope all I have to do is replace the sensor to get the CEL off. My goal for the first 6 months of this year with my XJ is to get the CEL off and get all my leaks fixed and a very thorough tune up. If I have to put exhaust on to fix the CEL thats going to slow the other stuff down as I only have about $200 set aside at the moment just for my Jeep. If I can do that I will start on some other cosmetic repairs (windshield, tires, lift etc.)