Do I need my after cat O2 functional?

97 4.0 aw4. This past weekend I got the xj pretty well hung up on the rocks at a local wheelin spot but it was probably the damn shrubbery that tore off my wiring to the rear o2 sensor... The thing is the truck seems to be running fine although the 'check engine' light is on. The rig is due (over due) for a tune-up so it could be running poorly and I might not even know it.

I seem to recall that after cat o2's do not affect pcm operation on these trucks but I may be totally wrong on this one.

Fix it or +?%k it till inspection time?

IIRC!!!!! The pre-cat sensor controls the PCM, the post cat sensor monitors the first one.. which would lead me to believe, that the post cat one is the one that kicks your CEL?!

I think you're both right. The first O2 sensor is used by the PCM to control the air/fuel ratio, and the second sensor is used to monitor how the catalytic converter is performing. If the cat isn't doing its thing well enough, it trips on the check engine light. Since you have no signal, that will definitely trip the light. If you can repair the wiring, just do that and you'll be done.