Unstable Engine and Excessive Fuel Consumption in 2012 Nissan Pathfinder: Possible Lambda Sensor Issues

Hey, I had a similar problem with my 2015 Nissan X-Trail, petrol engine as well, ticked off close to 47,000 KM. I was having engine instability issues and increased fuel consumption along with black smoke puffing out of the exhaust on acceleration. The check engine light seemed to have a mind of its own. Turns out the ceramic inside my lambda (oxygen) sensor was grimed up. The mechanic showed me the clog, which messed up the fuel/air mixture ratio, leading to poor performance and heavy fuel use. After a thorough examination, the garage staff cleaned out the lambda sensor, but the problems still persisted. Finally, they had to replace the entire lambda sensor. After replacement, my car started running smoothly: power was restored, no more aggressive fuel consumption, and no more check engine light. So, it wasn't just an aged sensor issue but a completely gunked-up one. It wasn't a small problem, but once sorted, it made a world of difference. You might wanna have your lambda sensor checked and possibly replaced. That should sort out most of the problems you're facing. Let me know how it goes!

(Translated from German)

Hey, thanks for sharing your experience! I'm really leaning toward the lambda sensor issue as you suggested. I've been worried about my poor Pathfinder and your advice has given me some clarity. Do you remember roughly how much it ended up costing you for the sensor replacement? And have any other issues arisen since you got it fixed? Cheers for your help!

(Translated from German)

Hey, glad to hear that my experience could give you some insight! As for the cost, the lambda sensor, including a thorough cleaning of the grimed-up ceramic inside, set me back 375€. Not exactly pocket change but trust me, it was worth every cent for the relief of having a smoothly-running car again. Ever since the sensor was fixed, my Nissan X-Trail hasn't given me any more problems. The engine’s been stable, no excessive fuel consumption, and I've kissed black exhaust smoke goodbye. The mechanic really did manage to hit the nail on the head with the diagnosis. So, here's to hoping your trusty Pathfinder's troubles will be a thing of the past once your Lambda sensor’s sorted. Keep me posted! Cheers!

(Translated from German)

Thanks a stack for letting me know! It does seem a bit pricey, but if it gets my Pathfinder running smoothly again, it'll be well worth it. I'll take it in for a check-up at my mechanic's and discuss the lambda sensor scenario. It's such a relief to have a starting point for the problem! I'll keep you in the loop about what the mechanic finds, can't wait for those improved miles per gallon! Thanks again for the advice and sharing your experience. I sincerely appreciate it! Cheers!

(Translated from German)