BMW 8 Series Transmission Crisis: Warning Signs & Solutions

Hey there! Had a similar issue with my 2021 BMW M5 last year. Those symptoms sound really familiar. My car was also stuck in limp mode with transmission warnings. After taking it to my trusted workshop, they diagnosed a faulty wiring connection to the transmission control module. Some cables were loose and had corroded connectors. Ended up paying 95 Euro for the repair, mainly labor costs to trace and fix the connection issues. The grinding during shifts completely disappeared after that. Before I can share more specific advice, could you share: What's your current mileage? When did these symptoms first appear? Any recent maintenance or repairs done? Transmission issues can be tricky, and BMWs can be quite sensitive to electrical problems. Let me know these details, and I might be able to help further based on my experience with both my M5 and previous 7 Series.

Thanks for sharing your experience with the M5! My BMW has 65513 KM on the clock and just had its latest service done. After reading your reply, I'm a bit relieved it might just be an electrical issue rather than a major transmission problem. The symptoms actually started right after a heavy rainstorm, which now makes me think water might have gotten into those connectors you mentioned. I'll definitely get those wiring connections checked first before assuming the worst. Good to know it was a relatively simple fix in your case and didn't break the bank. Really appreciate the insight!

Hey again! After reading about your car's symptoms starting after that rainstorm, I'm even more convinced we're dealing with the same issue I had. In my case with the M5, water had actually seeped in through a slightly damaged grommet near the transmission wiring harness, pretty common spot for water intrusion on these models. Quick tip from my experience: before taking it to the shop, check around the transmission area for any obvious signs of water damage or corrosion. I actually found some white residue around the connectors in my case, which was a clear sign of water exposure. One thing I didn't mention in my first reply, after my repair, I had them add some extra sealant around the wiring access points to prevent future water damage. Might be worth doing the same for yours. The extra 20 Euro for the sealant was totally worth it, haven't had a single issue since, even in wet weather. Also, since you mentioned your recent service, might be worth checking if they disconnected anything around the transmission during the service. Sometimes these connectors don't get seated quite right when they're put back together. Had that happen once on my previous BMW too. Let me know how it goes with the inspection. Pretty sure you'll be back on the road without spending a fortune!

This is incredibly helpful, especially the tip about checking for white residue around the connectors! I just went out to look at my car and found exactly what you described, there's definitely some corrosion around the wiring area. And you're right about the service timing too, they did mention working around the transmission area during the last service. I've already called my mechanic and scheduled an inspection for tomorrow morning. Mentioned everything we discussed, including the possible water damage and loose connections after the service. They seemed to know exactly what I was talking about and said they'd check those specific areas first. Really glad I asked here before panicking about a full transmission replacement! Will definitely get that extra sealant done too, sounds like a smart preventive measure. Thanks again for taking the time to share your experience. It's saved me a lot of worry and probably a good chunk of money too!