BMW 5 Series Audio & Nav Dead, MOST Bus Issue?

Hey there! I have some experience with car electronics, and I actually faced a similar issue with my 2012 BMW 3 Series (had this problem last year). The symptoms were identical, complete audio blackout, nav system dead, the whole deal. Took it to my regular workshop where I learned it was indeed a MOST bus problem, specifically a faulty control unit. They had to replace one of the control modules, which set me back about 1000 Euro. Wasn't fun for the wallet, but it fixed everything perfectly. Before suggesting more specifics, could you share: Does your iDrive screen work at all? Are you getting any specific error messages? Have you noticed any other electrical issues? By the way, I also own a BMW X3, and these MOST systems are pretty similar across the lineup. Let me know the details, and I can point you in the right direction based on my experience.

Just had my service done at 41547 KM, and I've been dealing with this exact same problem! The iDrive screen works fine, no error messages showing up there, but absolutely no sound and the nav is completely dead. Everything else electrical seems to be working normally. Thanks for sharing your experience, it's really helpful to know it was the control unit in your case. My mechanic initially thought it might be a simple fuse issue, but after reading your reply, I'll definitely have them check the MOST bus system and control modules specifically. Did your repair take long to complete once they identified the problem?

Hey again! Yeah, sounds exactly like what I dealt with on my 3 Series. Once they pinpointed the problem, the actual repair was pretty quick, took them about 2-3 hours to replace the control unit and get everything up and running again. I remember being relieved when they told me it wasn't anything more serious. The symptoms you're describing are almost identical to what I experienced, working iDrive screen but complete silence from the audio system. Your mileage is even pretty close to when mine started acting up (I was around 45000 km). Just a heads up though, make sure they do a proper diagnostic scan. Initially, my mechanic also thought it was just a fuse, but that would've been too easy, right? The MOST bus issue isn't always obvious without the right diagnostic tools. Have you noticed if the problem started suddenly or did it gradually get worse? In my case, it was like someone just hit an off switch, everything audio-related just died at once. After the repair, though, it's been working perfectly for over a year now. Let me know how it goes with your mechanic. Always happy to share more details about my experience if you need them!

Thanks so much for all this detailed info! That's super helpful to know it was a sudden failure in your case, mine was exactly the same way. One minute everything was fine, and the next, complete silence. Really reassuring to hear your repair has held up well for over a year too. I've booked an appointment with my mechanic for next week. I'll definitely make sure they do that proper diagnostic scan you mentioned and check specifically for MOST bus issues. The 2-3 hour repair time doesn't sound too bad either, I was worried it might take days! It's funny how our cars had such similar symptoms at almost the same mileage. Guess these BMWs like to keep us on our toes! I'll update this thread once I get it fixed in case anyone else runs into the same problem. Thanks again for sharing your experience, it's made me feel a lot more confident about getting this sorted out!