jpk

I'm going to be replacing my O2 sensors so in prep so I'm familiar with the area underneath I looked at mu DS sensor and the plug was completely disconnected. I started to look for where the other end was and couldn't find it. While under there I also noticed another plug that was disconnected. The bundle had one end plugged into the side of the transfer case, the other end? My Xfer case is a NP231 Command Trac. Any thoughts as to what the Xfer case plug goes to? And, where is the plug for the O2 sensor located? Thanks.

Also; I have already tested putting the XJ into 4wd and the dash indicator light comes on when I do.

Forgot to mention my XJ is a 96 model year.

A friend of mine suggested it may be for the electric lockers for the front wheels.

5-Speed

Can you post some pictures of these plugs?

awg

there is 2 x O2 sensors on a '96

pre-cat, (front) which matters a lot, and post cat (rear), which as far as I can tell, only warns of bad cat ( I just changed it anyway, as the PO had cut the wires, and the Cat did need replacing

be very careful before you buy new ones..'96 has some subtle variations in plug ends

what part can you not find?...the male connectors?..one is grey, one black ..4 recessed pins...or look for a cut wiring bundle with 4 wires

jpk

Just got under her this am to check it out closer. The wiring loom that contains whatever plugs into the Xfer case also contains the lead that goes to the DS O2 sensor. I thought that lead was supposed to plug into something else. So I reattached the sensor to the plug. I still got a CE light. I am going to replace both sensors anyway even if it went out since I have already bought them. So my next question is the lead that the sensor plugs into has a way to secure it to a mount in the drive shaft tunnel Where is that mount located?

awg

You have not said if its the rear sensor ur talking about ? ( I assume it is, as the thing wont run well with the front one disconnected)

The rear one has only one job in life...making sure your Cat is ok...as I understand it, they are the same sensor, and the PCM knows the post-Cat signal should be very different, once they become to similar, it means the Cat isnt working, throws a code. ( has no effect on engine operation)

mine was cut when I got it, generating a p0138 code....after a while the Cat started rattling.

I replaced Cat and sensor, the code P0138 was retained until I cleared it...strangely, the CEL was not lit (code needs clearing, it wont clear itself)

The sensor wires have a tab to poke onto some hole..not knowing where that was either..I just used a cable tie

My system has a 2.5" exhaust, with generic Cat, ordered one for $100 off Ebay..likely why yours is disconnected

jpk

I replaced both front and rear. An interesting thing. The computer threw a code saying the O2 sensor was bad, the CEL was on. So, I go to Autozone to get a 7/8ths sensor socket in prep to install the sensors. After buying the socket I get in the XJ, turn the key and nothing. There's a click and that's it. So the store guy puts a tester on the battery and said it was bad. It was starting a little slow for a while but I thought it was just because I don't drive it a lot. So, I just so happen to have bought the battery there and the it was under warranty. So I get a new battery for free and then, the CEL went out when I started the engine. I wonder if the battery may have been the issue if it was not putting out the voltage needed for the sensor. Regardless, I did replace both and it runs fine.