The check engine light came on in my GC, then when the weather was warmer and it ran better, the light went off. This has happened a few times during the winter. Went to Autozone to have the code checked out. It came back with defective sensor 1. The guy behind the counter could not tell me which one was sensor 1. Any help would be appreciated.
Thanks.

 

http://www.wjjeeps.com/oxygen.htm

If it's the 4.0l, I have the same problem and I've been ignoring it for the past year.

as of recently my MPGs have dropped to about 12... so I just ordered http://www.rockauto.com/catalog/more...692&cc=1420737

 

Rhode Island, huh? I grew up in Warwick. I left RI after my Navy tour. I still miss still mornings on the bay.

My 2000 WJ 4.0 is supposed to have 2 upstream sensors, but I haven't looked yet. I imagine they are the same part number. If you've got the 4.7, I can't help you because I haven't even seen a 4.7 yet.

 

Dave, I have the 4.0, Adam, my mileage has dropped too, and just yesterday, the check engine light went off, go figure! I'm at the point that I'm about to change all of them, and not have to worry about any of them.
Pete.

 

We carry new O2 sensors on our website with FREE SHIPPING. Here's a link to them for your 04 Grand Cherokee if you would like to see what we have. http://www.1aauto.com/1A/oxygen-sens...ampaign=1ATony