Jeep Cherokee O2 Sensor Issues Draining Your Tank

As someone with moderate experience working on similar vehicles, I faced nearly identical issues with my 2019 Jeep Grand Cherokee diesel last year. The symptoms you describe match my experience exactly, poor fuel efficiency and an illuminated check engine light. The initial diagnosis pointed to the oxygen sensor, but when the mechanic did a thorough check, they discovered the actual culprit was a loose connection in the sensor wiring harness. The air-fuel ratio was indeed affected, but it wasnt the sensor itself that needed replacement. The fix involved securing the cable connections properly and testing the oxygen sensor functionality. Total repair cost was 95 Euro, which included diagnostic time and labor. After the repair, fuel consumption returned to normal and the check engine light cleared. For a more accurate comparison, could you share: Current mileage on your Cherokee, When you first noticed the increased fuel consumption, Any other unusual behaviors or sounds, Whether the check engine light is steady or flashing, If you notice any exhaust smoke or unusual odors This information would help determine if your situation matches what I experienced with my similar vehicle during car maintenance.

Thanks for the useful information about the wiring harness. The latest service was done at 35000 KM during routine maintenance, and current mileage is 39670 KM. The check engine light has been steady, no flashing. Initially I thought the catalytic converter might be the issue, but the diagnostic codes point more toward the O2 sensor. No unusual exhaust smoke or smells noticed, and the engine runs smoothly otherwise. Fuel consumption started increasing about 2 weeks ago. Did your mechanic check the exhaust system components beyond just the oxygen sensor? The automotive sensor readings show consistent issues with the air-fuel mixture.

From my experience with the same issue on my Cherokee, its worth noting the similar timeline. My problems started around 38000 KM, close to where you are now. The wiring harness fix solved most issues, but our mechanic did perform a complete exhaust system inspection. Looking at your mileage and symptoms, this matches the pattern I encountered. While the catalytic converter was initially suspected in my case too, the diagnostic codes correctly pointed to the oxygen sensor area. The steady check engine light, rather than flashing, is another similarity that suggests we dealt with the same issue. The fact that your automotive sensor shows consistent air-fuel mixture issues reinforces my experience. Our mechanic explained that even a partially failing O2 sensor connection can cause these symptoms while allowing the engine to run smoothly otherwise. For reference, after fixing the wiring, they also tested the catalytic converter efficiency using the proper diagnostic tools, something worth requesting in your case. The entire diagnostic process cost about 120 Euro, but prevented unnecessary parts replacement. Given the matching symptoms and timing, recommend having them check both the wiring harness and the oxygen sensor itself. In my case, the actual sensor was fine, saving considerable replacement costs.

Thanks for the detailed follow-up about your Cherokee repair experience. After hearing about your wiring harness diagnosis, I made an appointment with my mechanic for tomorrow morning. They mentioned theyll do a complete check of the exhaust system components and test both the oxygen sensor and its connections. Your situation does sound remarkably similar, especially with the steady check engine light and fuel efficiency issues starting at comparable mileage. The lack of exhaust smoke in both cases also suggests a similar root cause. While my automotive sensor readings still indicate an air-fuel mixture problem, Im now more hopeful its just a wiring issue rather than a complete O2 sensor failure. Will update once the mechanic completes their diagnostic process. Its reassuring to know it might be a simpler fix than initially expected, similar to your experience. The potential 120 Euro diagnostic cost seems reasonable to avoid unnecessary parts replacement.