BMW 7 Series Trans Issues: TCU Failure or Something Else?

Hey there! I have some experience working on cars and went through something very similar with my 2013 BMW 5 series (also had a 3 series before). Last year, I had nearly identical symptoms, jerky shifts, grinding, and the transmission going into limp mode. After taking it to my trusted mechanic, it turned out to be a faulty transmission control unit. The diagnosis was spot on. Had to get the control unit replaced which set me back about 1000 Euro, but it fixed the problem completely. The transmission has been shifting smoothly ever since. Can you share more details about your car, mileage, service history, and when exactly these symptoms started? This would help determine if you're dealing with the same issue or if there might be something else going on.

Thanks for sharing your experience! My car has 145672 KM on the clock and just had its service last month. The symptoms started pretty suddenly about a week ago, getting worse each day. What's interesting is that the problems you described match mine exactly, especially that grinding noise during shifts. Good to know your fix worked well with just the control unit replacement. Did you notice any warning lights on the dash before the transmission started acting up? The repair cost sounds reasonable compared to what I was worried it might be. Were you able to drive the car to the shop or did you have to get it towed?

Hey again! Yes, this really sounds like what I experienced with my BMW. To answer your questions, I actually did notice the transmission warning light on the dash about 2-3 days before things got really bad. At first, I ignored it since the car was still driving okay, but that was probably not the smartest move. I managed to limp the car to my mechanic, but honestly, I should have had it towed. I drove really carefully and kept the speed low, but with these transmission issues, it's better to be safe than sorry. You don't want to risk causing more damage. What's interesting is that my service history was also pretty clean, just like yours. Had regular maintenance done and everything. The control unit just decided to give up suddenly. From what my mechanic told me, it's not uncommon with these models after they hit around 140-150K kilometers. Since you mentioned the grinding noise is getting worse each day, I'd strongly suggest getting it checked ASAP. My experience taught me that these symptoms don't get better on their own. The sooner you get it fixed, the less chance of damaging other transmission components. By the way, after the repair, did you notice any other electrical issues? My power windows started acting up right before the transmission problems, but that actually turned out to be unrelated. Just curious if you've experienced anything similar.

Thanks a lot for all those details! Really helpful to hear about your warning light experience. I've actually seen the transmission warning light flashing on and off too, so that's another sign pointing to the control unit. I think I'll take your advice and get it towed to avoid any extra damage. Better to spend a bit on towing than risk making things worse. It's weirdly reassuring to hear that these issues are somewhat common at this mileage, makes me feel less like I've done something wrong with the maintenance. Funny you mention electrical issues, I haven't had any problems with the windows, but my seat memory settings have been acting up lately. Probably unrelated like in your case, but interesting coincidence. I'll get in touch with my mechanic first thing tomorrow and mention the control unit possibility. The repair cost you mentioned gives me a good baseline for what to expect. Really appreciate you taking the time to share your experience, it's definitely helped me understand what I'm dealing with!