M2 Infotainment System Complete Failure: MOST Bus Issues

Hey there! I have some experience working on cars and had a similar issue with my 2020 M4 last summer. The symptoms were exactly the same, complete infotainment blackout. After taking it to my trusted workshop, they diagnosed a faulty control unit in the MOST bus system. The whole repair took about 2 days, and I ended up paying around 1000 Euro for the new unit plus labor. Before going to the shop, I tried the basic troubleshooting like disconnecting the battery for 15 minutes to reset the system, but nothing worked. Could you share your car's mileage and whether you've noticed any other electrical issues before this happened? Also, did you get any specific error codes that might help narrow down which control unit is causing the problem? Feel free to ask more questions, this can be pretty frustrating to deal with, but it's usually fixable!

Thanks for sharing your experience! My M2 has 157305 KM on the clock, and the last service was just done a couple months back. I actually did try the battery disconnect trick as well, but no luck. The error codes I got were pointing to MOST bus communication failures, but nothing more specific than that. Haven't noticed any other electrical gremlins before this happened, it just went completely dark one morning. Really appreciate the cost estimate, helps me prepare for what's coming. Did you notice any warning signs before your system completely failed? I'm hoping to get this sorted quickly since I use navigation quite a bit.

Hey again! Thanks for the follow-up info about your M2. You know, thinking back to my M4's situation, it also went dark without any warning signs, just woke up one day and boom, nothing worked. Pretty similar to what you're experiencing. Since you mentioned you just had service done recently, I'd suggest checking if they might have accidentally disturbed any connections during the work. In my case, the workshop first thought it might have been just a loose connection, but it turned out the control unit itself was toast. With your mileage being around 157k, it's actually not uncommon for these MOST bus components to start failing. Mine had about 145k when it happened. The good news is, once it's fixed, it usually stays fixed, I haven't had any issues since the repair last summer. One thing I learned from my experience, make sure they do a complete diagnostic on the entire MOST ring when they fix it. In my case, they initially only replaced the faulty unit, but had to recheck everything when the system still acted up. Turns out there was a slight issue with the fiber optic connection too. Want me to share what specific tests they ran on my car? Might be helpful when you take yours in.

Thanks so much for all this detailed information! Yes, I'd really appreciate knowing what tests they ran on your car, that'll definitely help me be more informed when I take it to the shop. Good to know about checking the entire MOST ring too. I'll make sure to mention that to them. Actually feeling a bit better about this whole situation now, knowing it's a somewhat common issue and there's a clear fix. I was worried it might be something more complex or expensive. Sounds like I just need to bite the bullet and get it sorted. I'll get it booked in tomorrow and hopefully have it back on the road soon. Really appreciate you taking the time to share your experience and tips, it's been super helpful!

I too have difficulty understanding or improving and erasing certain faults.

(Translated from French)

If you're having trouble with fault codes, start by using an OBD-II scanner to read the specific error codes from your vehicle. This will give you a clearer idea of what might be causing the issue. Once you have the codes, you can look them up to understand what they mean and what components might be affected. If you're unsure or if the issue seems complex, it's always a good idea to consult with a professional mechanic. Let me know if you need help with specific codes or further guidance!