I'm confused on this one. I've searched and found a lot of info about getting the codes (key on-off, hold trip button, etc etc), but the only thing I can get the odometer to display is code 2.3? Of course that isn't in any list I've found... what is that?

Do I have to use a scanner to get the code(s) for my check engine light?

 

That is not a code of any sort, sounds like your trip odometer has logged 2.3 miles. Vato Zona can scan for stored codes.

 

Yea.... it's not the trip odometer (that's at 31 miles). Plus I've read other have the same thing. I see what the local parts store can tell me.

 

Ok.... the advanced Auto parts scanner says it's the O2 sensor Bank 1 (Upstream?), but I see the wires are off the downstream sensor (broken/missing).

Would that cause the upstream code? There was no downstream (bank 2?) code... or any others for that matter.

 

You can't do the key trick on the newer XJ's. I think it stopped in the early 90's.

 

It sounds to me like you need to repair/replace your O2 sensor(s). The upstream sensor sends data to the PCM and with other sensors input determines fuel flow and other performance criteria. The downstream sensor monitors the exhaust emissions. If your cat isn't performing within a certain range, the downstream O2 trips the CEL. Unless you have dual exhaust, you only have two O2 sensors, up and downstream. Bank 1 or 2 would indicate which side on a dual exhaust system. I'd fix the sensors. Hope this helps.

 

Bank 1 sensor 1 = upstream
Bank 1 sensor 2 = downstream

 

left and right cylinder bank... makes sense. I ordered a downstream sensor.

Any hints on getting that thing off? I tried soaking with liquid wrench, running the engine (heating it up), but it's on there pretty good! Before I rip the exhaust out trying the wrench this off... are there any tips to this one. How about the upstream?

 

Left and Right banks only apply to 2000+ model year 4.0s that have a total of 4 O2 sensors, all installed in the exhaust manifold.

I tried everything I could in my driveway to get my upstream sensor off my 1999... I think it was original. Took it to a garage where they heated it with a torch until it was glowing red hot. Even then it took quite some effort to get off!

 

Some O2 sensor sockets have thin walls and will open during extreme torque. I bought one that is heavy duty and it works well, but if you know you're going to replace it I'd just hacksaw the top off then try a 1/2" breaker bar with a pipe and a tight fitting impact socket, or pick up a deep well impact socket. All that after soaking it several times with PB Blaster and heating the bung with a MAP gas torch.

 

Agree. Break the top off, and then you can get a regular socket on there.