BMW 6 Diesel Performance Issues, Knock Sensor Suspected

Hey there! I've got some experience with BMWs as I had a similar issue with my 2016 BMW 4 Series diesel (also have a 3 Series in the family). Your symptoms sound really familiar. Had almost the exact same thing happen, engine light, poor performance, the works. Initially thought it was something major, but turned out to be just a faulty wiring connection to one of the sensors. My mechanic found a damaged cable and corroded plug connection that was causing all these issues. Got it sorted for about 95 Euro, mainly labor costs for diagnosing and fixing the connection. Could you share what BMW 6 variant you have (640d, etc.)? Also, are you getting any specific error codes? This would help me give you more targeted advice based on my experience. BTW, I'd say I have some experience with BMWs, but I'm no expert, just learned from dealing with my own cars over the years.

Thanks for sharing your experience! My 640d just hit 133,219 km, and it just had its service last month. The error code reader shows P0327, which makes me think it's definitely sensor-related like you mentioned. Though I haven't checked the wiring yet, that's a great suggestion. I was worried it might be something more serious, so hearing about your similar experience with the wiring issue is quite relieving. Especially since the repair cost wasn't too bad in your case. I'll have my mechanic take a look at the connections first before replacing any parts. Did your car's performance return to normal right after the repair?

Hey again! Yeah, my 4 Series was showing that exact same error code when I had the issue. After the wiring fix, it was like night and day, the performance bounced right back to normal. The sluggish acceleration disappeared completely, and my fuel economy went back to what I was used to. Just to add to what I mentioned before, when my mechanic was checking the wiring, he also found that some debris had gotten caught near the connector, which contributed to the corrosion. Might be worth having them check for that too. The whole repair took less than two hours, and my car's been running smooth as butter since then. Given that your 640d just had a service and is showing the same symptoms and error code as mine did, I'd bet good money it's a similar wiring issue. One thing I learned from my experience, these sensors are pretty robust, but the connections can be a bit finicky sometimes. Keep us posted on what you find out! Always interested to hear how these things turn out, especially since we BMW owners tend to run into similar issues.

Thanks so much for all the detailed info! It's super helpful to hear that your car got back to normal right after fixing the wiring. I've actually just booked my car in for tomorrow morning, and I've specifically asked them to check the wiring connections first, along with looking for any debris like you mentioned. Really hoping it'll be a similar quick and affordable fix like yours was! You've saved me a lot of worry, I was honestly expecting to hear I'd need to replace the whole sensor or worse. I'll definitely update this thread once I get it sorted. Thanks again for taking the time to share your experience, it's exactly what I was looking for when I posted this question!