My 2000 XJ with a 4.0L engine has come up with a P0171 code. I changed the plugs a few weeks ago, as I had a occasional stumble. Just prior to changing the plugs I got a P0171 code. Changed the plugs, reset the code and all seemed fine. The XJ has just over 177000 miles on it. The wife has been driving the Jeep for a couple of weeks now with no problems and no error codes. Today we went to go to a tractor show and shortly after getting on I-75 I got a check engine light. Came home and took our Grand to the show. When we got home I checked the code and once again I had a P0171. I think the O2 sensors are the original ones that where in the vehicle. I was wondering if the upstream O2 sensor could be getting flaky. Outside of the P0171 code being on the XJ seems to run fine. I don't want to keep driving it though and risk engine damage. Open to any and all ideas and any test procedures I should try. I did test the fuel press and it is right in specs.
Thanks,
Bill
Thanks,
Bill