BMW M4 Transmission Nightmare: Grinding & Shifting Issues

Hey there! I had a pretty similar issue with my 2013 BMW M3 last year. The symptoms you're describing ring a bell, my transmission was acting crazy too. After a lot of headache, it turned out the transmission control unit was faulty. Had to take it to my trusted workshop, and they diagnosed it with their diagnostic tools. The fix wasn't cheap, cost me around 1000 Euro for the new control unit and programming. The M6 I had before never gave me such trouble, so this caught me off guard. Before you head to the workshop, could you share: How many miles/km on your M4? When did these symptoms start? Are there any warning lights on the dash? This info would help me give you more specific advice based on my experience.

Thanks for your response! My M4 has 19166 KM on the clock and just had its service last month. The symptoms actually started about a week ago, and yeah, I'm getting a transmission warning light on the dash. It's really frustrating because it was running perfectly fine before this. The grinding noise is what worries me the most, it happens especially when shifting from 2nd to 3rd gear. Your experience with the control unit issue sounds pretty similar to what I'm dealing with. Did you notice any grinding sounds before getting it fixed?

Hey again! hearing about those grinding noises definitely brings back memories of my M3 troubles. Yeah, I actually did experience similar grinding sounds, especially during those 2-3 shifts, it's like déjà vu hearing you describe it. My car had about 25000 KM when it started acting up, so yours having issues at 19166 KM isn't too far off. The transmission warning light is exactly what I got too. Honestly, those grinding noises were what pushed me to get it checked out ASAP, didn't want to risk more damage to the transmission. When my control unit was replaced, all those symptoms, the grinding, the rough shifts, the warning lights, completely disappeared. It was like getting a new car again. Though I have to say, I also got them to flush the transmission fluid while they were at it, just to be on the safe side. Quick tip from my experience, don't keep driving it too much with these symptoms. I made that mistake for a few days and really regretted it. The grinding especially isn't something you want to ignore. These M transmissions are pretty robust, but when they act up, it's usually something that needs immediate attention. Let me know what your mechanic says when you get it checked out. Really curious if it turns out to be the same issue as mine.

Thanks so much for all the detailed info, this is super helpful! You're absolutely right about not driving it too much. After hearing about your experience, I've already called the workshop and booked it in for tomorrow morning. Better safe than sorry, especially with that grinding noise! Really hoping it's just the control unit like in your case. The price tag isn't fun, but it's better than having to replace the entire transmission. I'll definitely have them check the transmission fluid too, that's a good suggestion I hadn't thought about. It's actually quite reassuring to hear someone else went through the exact same thing and got it sorted. I'll let you know what they find out. Thanks again for taking the time to share your experience, really appreciate it!