BMW 2-Series Start-Stop Failure While Driving

I had a similar issue with my 2011 BMW 1 Series diesel. Battery-related problems can be tricky, and I learned this firsthand. Last month, my car showed the same symptoms, start-stop failure, unusual engine shutoffs, and warning lights. Took it to the garage and they found that my battery was severely degraded. The alternator wasn't charging it properly anymore. It was serious because a failing battery in modern diesels can cause multiple system malfunctions, including those unusual shutdowns you're experiencing. They had to replace both the battery and alternator. The original battery had lost most of its capacity to hold charge. Since the fix, the start-stop works perfectly, no more shutdowns, and all warning lights are gone. Your symptoms match my experience exactly. Given that these issues affect safety systems, I'd recommend getting it checked soon. Make sure they do a proper battery load test, not just a voltage check.

Thanks for sharing your experience with this! Really helpful as it sounds exactly like what I'm dealing with right now. I've been worried about finding a trustworthy mechanic for this. Quick question, do you remember roughly how much the battery and alternator replacement set you back? Also, just curious if you've had any other electrical gremlins pop up since getting it fixed?

Hey again! Happy to give you a follow-up on my BMW situation. Just wanted to let you know that I actually only needed the battery replacement in the end, I was wrong about the alternator being part of the problem. The total cost came to 290€ for diagnosing and fixing the heavily discharged battery. Much cheaper than I initially feared! Since getting it sorted, everything's been running perfectly. The start-stop system is working like new again, and I haven't seen any of those annoying warning lights or experienced any shutdowns. It's such a relief not having to worry about the car out of nowhere cutting out anymore. No other electrical issues have popped up at all, it really was just the battery causing all the drama. Modern BMWs can get pretty fussy when the battery starts failing, but once you sort that out, they're solid. Trust me, getting this fixed properly is worth every penny. Hope this helps give you a better idea of what you might be looking at cost-wise!

Thanks so much for the detailed follow-up! I actually just got back from the mechanic today. You were spot on, it was the battery! Mine was completely shot and apparently wasn't holding charge properly anymore. Got it replaced and the difference is like night and day. Total bill came to about 320 for everything, including diagnostics. A bit more than yours but still way better than what I was expecting. The mechanic I found was really honest and even showed me the test results from my old battery. The start-stop system is working perfectly now, and those scary unusual shutoffs have completely stopped. No warning lights either. Should've done this weeks ago instead of worrying about it! Really appreciate you sharing your experience, it helped me understand what I was dealing with and gave me confidence to get it sorted. Funny how something as simple as a battery can cause so many weird problems in these modern cars. At least it's all sorted now!