BMW X1 Knock Sensor? Engine Light & Performance Issues

Hey there! I have some experience working on BMWs. Actually had a similar issue with my 2014 BMW X3, and my cousin owns an X5. Like you, I had the check engine light, poor acceleration, and fuel economy issues. Turned out it was a loose connection in the wiring harness going to the knock sensor. The workshop diagnosed it pretty quick, they found the cable connection was worn and not making proper contact. Total fix was 95 Euro, mostly labor costs since they had to access some tight spots to get to the wiring. Before I can give more specific advice, could you share: Have you scanned for error codes? Any unusual sounds when accelerating? When did these symptoms first appear? This info would help determine if you're dealing with the same issue I had. BMWs can be tricky, but once you pinpoint the problem, it's usually straightforward to fix.

Thanks for the detailed response! I've got similar symptoms on my X1 with 148936 KM on the clock. Just had it scanned yesterday and got error code P0325. Started noticing these issues about two weeks ago, right after my latest service actually. And yeah, there's this weird knocking sound when I accelerate, especially going uphill. Your wiring harness story gives me hope it might be something simple like that rather than having to replace the entire sensor unit. I'll definitely have the mechanic check the connections first, could save me some money if it's just a loose wire like in your case.

Hey again! Had to jump back in after seeing your mileage and that P0325 code. The symptoms you're describing are exactly what I experienced with my X3, especially that knocking sound on acceleration. It's almost like déjà vu! Since you mentioned it started after your service, I'd bet money they might have disturbed something while working on the car. That's actually similar to what happened to me, my issues started after some routine maintenance too. When they were checking around the engine bay, they probably moved some wiring around and didn't secure it properly. Just to add to my previous reply, when they fixed my wiring harness issue, the knocking sound disappeared completely and my fuel consumption went back to normal within the next tank. The engine management system was obviously getting confused by the faulty signals. Quick tip from my experience, make sure they check the connector pins too, not just the wiring. Mine had a bit of corrosion that needed cleaning. If you're really lucky, it might just need a good clean and secure connection rather than any new parts. My cousin's X5 had the exact same issue and that's all it needed. Would love to hear what your mechanic finds. Keep us posted!

Thanks so much for all this info, it's super helpful! It's really reassuring to hear both you and your cousin had such straightforward fixes for similar issues. I've already called my mechanic and booked it in for tomorrow morning. Mentioned everything you said about checking the wiring harness and connector pins first. They seemed to think it was a reasonable place to start, especially given the timing after the service. You've definitely saved me some stress here, I was imagining much worse scenarios! I'll make sure they thoroughly check all the connections before jumping to replacing any parts. The corrosion tip is particularly useful, I'll specifically ask them to look for that too. Will definitely update the thread once I get it sorted. Really appreciate you taking the time to share your experience in such detail.