darktower

I have a 2001 cali jeep cherokee sport 4.0 and it recently failed the emissions test. The Tech said it was a misfire on cylinder 4 and a bad reading on the o2 sensor bank one on the downstream. I replaced it with the NTG, however the 1st one would not connect and the 2nd one was twice as long as my original. So I had to wait for another to be ordered. When I tried to install (the "correct" one) it was so short it rubbed my linkage. so again I took it back. They then sold me another brand that was supposed to be same as the original, but it was still shorter than mine but usable. After driving 150 miles or so the check engine light came back and read the same issues. So the tech said it could be a bad injector on cylinder 4 causing the problem, so I replaced it but it came back on again with the same problems. Now he asked if I checked the o2 sensor fuse, (did not know there was one but sure would've been nice to know that before I spent money on the other things). Anyway I am new to the forum My fuses are unmarked and although I saw a thread about a similar issue, the fuse box it shows does not look like mine. can someone post some pictures indicating which fuse is the o2? Driving me as crazy as my avatar looks......thanks

Ralph77

Guessing you are talking about the O2 heater fuse that is in the PCM. Fuse box in the engine compartment. 15 amp.


WRONG PICTURE. I removed. Appears that they made a change in '00 for the PCM. See below.

darktower

Thanks Ralph, the fuse you are pointing at, that spot is empty on mine and where there is a twenty, mine is a 15....If I had recently bought it I would think someone took it out, however, I have had it 5 years and I do not believe I've ever looked in that fuse box before. It could be that my stepson removed it for some reason but he says he did not but....I appreciate your response and I will put one in that blank spot and while I am at it I will put a 20 where indicated in the picture and see what happens. thanks again!!!!

Ralph77

No Stop. I grabbed that of the internet. Maybe a different year and a different location. I replaced my O2 heater fuse because I was getting a code in my '00 but can not remember which one. Do not start putting fuses in places that do not have one. It was 2 years ago but almost positive that it was a 15 amp. Just check all the fuses that are in there for a blown one.

Ralph77

I am so sorry. Appears that pre '00 PCM layouts are a little different. Also I replaced a 20 amp not a 15 amp. I keep every receipt for everything I do to my '00 XJ. I went and dug it out. I believe this is the diagram you need. Fuse that reads O2S Relays. Again so sorry for the misinformation.

darktower

thanks Ralph, the new picture is my layout, but it seems all the 15's and 20's are ok so I guess I am back to square one. If you have another idea I would appreciate any input...thanks again.

Ralph77

First let me apologize for the misinformation. When you wrote:

Thanks Ralph, the fuse you are pointing at, that spot is empty on mine and where there is a twenty, mine is a 15....If I had recently bought it I would think someone took it out, however, I have had it 5 years and I do not believe I've ever looked in that fuse box before. It could be that my stepson removed it for some reason but he says he did not but....I appreciate your response and I will put one in that blank spot and while I am at it I will put a 20 where indicated in the picture and see what happens. thanks again!!!!

All sorts of bells and whistles went off in my head. Never even occored to me that the '00 and up PCM's were different then '99 down. I had a P0141, least I think that is what it was, which is an O2 Sensor Heater Circuit Malfunction. That fuse was blown and replacing it fixed my problem. Exactly what code are you getting? You say a misfire on cylinder 4. So P0300 and P0304? Did anybody look at the spark itself? Also not that I know from personal experience but most people on the forums will tell you to only use NTK O2 sensors. Wonder if the other brand is causing a problem. Coil bar too could be messing with the #4 cylinder plug. So if I remember correctly the bank 1 downstream O2 sensor in NTK was part # 23110? Length of the wire is 9.5". Got the length off the Napa site. How does that length compare to the original. I have an '00 CA emissions 4.0. With 4 O2 sensors. I swapped out all 4 just because. Remember wire lengths being different but no problems hooking them up. My thinking is that the O2 sensors fit more then one application and that would account for the different wire lengths. I know first hand the possibility of a part being defective from the get go or packaged wrong. Work in an auto parts store. Realize none of this really helps but it is things that I think need to be sorted through. If nothing else to rule them out.

wizardpc

Check the wiring at the O2 sensor.

Mine recently got away from the retainer and ended up touching the driveshaft. Needless to say the wiring didn't last long after that.

It happens a lot, apparently.