BMW X7 Trans Issues: Grinding & Random Gear Shifts Help

Hey there! I had some experience with a similar issue on my 2018 BMW X5 (also have an X3 in the family). I've got some experience working with cars, but I'm no expert. When my transmission started acting weird with similar symptoms, I took it to my regular workshop. After running diagnostics, they found the transmission control unit was defective and needed replacement. The whole thing, including parts and labor, cost me around 1000 Euro. They had it fixed in about two days, and it's been running smoothly since. Before I share more specific details that might help, could you share: What transmission error codes are you getting? Did the issue start suddenly or gradually? Have you had any recent transmission maintenance done? This way, I can better compare it with what happened to mine and give you more relevant advice.

Thanks for the detailed response! My X7 has only 6575 KM on it, and I just had the latest service done last month. The issue popped up pretty suddenly last week. I'm getting error code P0705, which from what I understand is related to the transmission range sensor circuit. It's frustrating dealing with this on such a new car. I'll definitely check the transmission control unit you mentioned, that could explain the erratic behavior. Did you notice any warning lights on your dashboard before the complete failure? Considering the low mileage and recent service, I'm hoping it's just a sensor issue rather than something major with the transmission itself.

Hey again! Thanks for providing those details about your X7. Yeah, I totally get your frustration, dealing with transmission issues on a nearly new car is really annoying. You know what's interesting? My X5 also threw that same P0705 code when my problems started, but I didn't get any warning lights until about a day before things got really bad. In my case, it was actually a faulty transmission range sensor, not the whole control unit like I initially thought. That's actually good news for you, it's a much simpler fix than what I was worried about in my first response. My workshop replaced the sensor, and it cost way less than the control unit job I mentioned before, somewhere around 300-400 in parts and labor. The repair took just a few hours, and I haven't had any issues since. Given that your car is so new and recently serviced, I'd bet you're dealing with the same thing. The sudden onset matches my experience too. Since you're still under warranty, I'd take it straight to the dealer, they should cover this kind of fault. Just make sure to document everything, including when the problem started and what symptoms you're experiencing. Want me to share what specific symptoms I noticed right before the sensor completely failed? Could help you confirm if we're dealing with the same issue.

Thanks so much for clarifying that! It's actually a huge relief to hear your experience was just a sensor issue. I was really worried I'd be looking at a major transmission repair on a practically new car. The symptoms you described match mine exactly, especially that bit about not seeing warning lights until things got worse. I'll definitely take it to the dealer since it's under warranty. The fact that your repair was relatively simple and quick makes me feel much better about the whole situation. Would really appreciate if you could share those pre-failure symptoms you mentioned, I'd like to know what to watch out for in case things start getting worse before I can get it to the shop. Thanks again for all your help and for sharing your experience. It's super helpful to talk to someone who's been through the same thing, especially with these high-end cars where every little issue can feel like a potential disaster!