My son is 16, his first car is a 1990 jeep cherokee laredo 4.0 straight 6cyl. We are learning as we go with this thing. the issue we are haveing now is the emission maintenence light is on. we have changed the 02 sensor,the guy at the parts store said the gas cap needs to be tight also,we did,the light is still on 2 days later. my question is: Does that light need to be reset or is there something else we need to look at? Would it throw a code? Thanks for any help you guys can offer.

 

Did you reset your ECU by unplugging the battery for a few minutes? Doing that will allow it to "re-learn" itself. If it comes back on after awhile then that definitely means something else is wrong. Sometimes the light will stay on even after the fix, and all it needs is a little reset! Exactly what code was it throwing at you?

 

Awesome! My first car was a '71 AMC Hornet. With nearly the same motor, lol.

That light doesn't function like those in newer vehicles. in '90 it's triggered by a timer as a reminder to renew the 02 sensor, etc. Comes on every 70K miles or something like that. It doesn't mean anything is wrong.
It can't be reset, the dealers just replaced them. Of course they probably aren't available anymore.
You can remove the timer box (behind the kickpad on the driver's side, just right of the steering column) and toss it, or just pull the bulb.

 

Welcome to the forum. Your XJ is Renix. Renix is pre-OBD, so no codes.

 

Hehehe my bad....