BMW M4 Trans Issues: Limp Mode & Shifting Problems Help

Hey there! I can relate, had a similar issue with my 2012 BMW M3 last year. I've got some experience working on cars, but transmissions are tricky business. My car showed almost identical symptoms, strange shifting, warning lights, and that annoying limp mode. Took it to my trusted workshop and turns out it was an undervoltage problem that was messing with the transmission control unit. They diagnosed it, fixed some electrical connections, and reset everything. Cost me around 240 Euro, but it's been running smooth since then. Before jumping to conclusions about the transmission fluid though, can you share more details? Like, when does it usually act up (cold starts, after driving for a while)? And what specific warning lights are you seeing? This could help narrow things down, as BMWs can be pretty complex when it comes to electrical gremlins.

Thanks for sharing your experience! Just had my latest service 2 months ago at 164969 KM, and these symptoms started showing up recently. In my case, it mainly acts up when the engine's warm, about 15-20 minutes into driving. The transmission warning light is solid amber, not flashing. Interesting that yours was an electrical issue, that's actually a bit reassuring since it might not be a full transmission rebuild situation. Did your mechanic mention any specific diagnostic codes? I've got a feeling I might be dealing with something similar, but wanted to gather some real-world experiences before heading to the shop.

Hey again! Thanks for those extra details about your M4. Those symptoms you're describing sound really similar to what I dealt with, especially that amber warning light. And the timing of it happening after the car's warmed up? That's exactly what I experienced too. When I had my M3 looked at, they pulled codes P0700 and P0785, which pointed to the transmission control module. Since you mentioned having similar symptoms after warming up, I'm even more convinced it could be electrical like mine was. The TCM can get finicky with heat, which explains why it acts up after driving for a bit. Just to be clear, mine also started showing these issues not long after a regular service, which had me initially worried about the fluid too. But looking back, the fluid wasn't the culprit at all. The heat-related electrical issue was causing the TCM to throw the car into limp mode as a safety measure. If I were you, I'd definitely get those codes read first before assuming it's a fluid issue. From what I've learned with these BMWs, the transmission control systems can be super sensitive to electrical problems. My fix was way cheaper than what I initially feared, and I really hope you'll have similar luck with yours. Keep us posted on what you find out, always interested in hearing how these things turn out!

Thanks so much for the detailed follow-up! You've actually made my day a bit better, I was dreading a massive repair bill, but hearing about your electrical fix gives me hope. Those codes you mentioned are really helpful info. I'll definitely get mine scanned first thing tomorrow. Come to think of it, the timing of my issues matching yours (after warm-up) really does suggest it could be heat-related electrical problems rather than fluid. Makes total sense about the TCM being sensitive, these cars are pretty high-tech after all. I've already called my mechanic and booked it in for next week. Asked them specifically to check the electrical systems and TCM based on what you've shared. Will share an update once I know what's going on with mine. Really appreciate you taking the time to share your experience, it's given me a much better idea of what to expect. Thanks again for walking me through this. It's amazing how helpful car communities can be!