BMW X3 Diesel Problems: Multiple System Failures & Stalling

Hi there! I have some experience working on cars and had a pretty similar issue with my 2021 BMW X4 diesel last year. Those symptoms sound very familiar, my X4 was doing almost the exact same thing. Turned out it was indeed a faulty connection with the boost pressure sensor. The cable had some wear and wasn't making proper contact. My mechanic found it during diagnostics, and it was a relatively straightforward fix. Cost me about 95 Euro for the repair, which included fixing the connection and clearing the error codes. What's your current mileage on the X3? And have you noticed if these symptoms get worse in any particular conditions (cold starts, high speeds, etc.)? This info would help confirm if it's the same issue I dealt with. Just as a tip, I'd recommend getting it checked soon. In my case, the poor connection was causing the engine to run rich, which explains the higher fuel consumption you're experiencing too.

Thanks for sharing your experience! My X3 has 64955 KM and actually had its last service just 2 months ago. I've noticed the symptoms are definitely worse during cold starts and when the engine isn't fully warmed up. The fuel consumption has gone up by about 3L/100km compared to normal. I'll get it checked out ASAP, good to know it might be a relatively simple fix like in your case. Did you have your repair done at a BMW dealership, or did you use an independent mechanic? I'd really appreciate it if you could share where you got it fixed since the pricing sounds pretty reasonable.

Hey again! Glad I could help earlier. Looking at your mileage and symptoms, it's even more similar to what I experienced with my X4. I actually took mine to an independent BMW specialist mechanic rather than the dealership, saved quite a bit of money that way. Just to add to my earlier response, after getting mine fixed, I realized the cold start issues were definitely related to the sensor problem. The ECU wasn't getting accurate boost readings during cold starts, which made the engine run really rough until it warmed up. It's exactly what you're describing. One thing I forgot to mention earlier, before I got it fixed, I tried cleaning the sensor and connections myself, but that only helped temporarily. The proper repair with new wiring ended up being the only real solution. The symptoms would always come back after a few days when I just cleaned it. My repair cost was lower because I went with the independent specialist. The dealership quoted me almost triple the price for basically the same work. Just make sure whoever you choose has experience with BMW diesels, they can be a bit tricky with these kinds of issues. Keep us posted on what you find out. Really interested to hear if it's the same issue I had.

Thanks so much for all the detailed info! That's super helpful, especially about trying to clean the sensor yourself first, definitely saves me from wasting time attempting that. And good to know about the independent specialist route too. The fact that your symptoms were so similar, especially with the cold starts, makes me pretty confident it's the same issue. I've already called a few independent BMW specialists and found one with good reviews who quoted me a reasonable diagnostic fee. They can look at it tomorrow morning, actually. I'll skip the dealership since, like you said, they tend to charge way more for the same work. Really appreciate you taking the time to share your experience, it's helped me understand what I'm dealing with and saved me from panicking about potentially major engine problems. I'll make sure to update the forum once I get it fixed so others with similar issues can benefit too!