Dead VW MOST Bus Kills All Infotainment Functions

Had the same issue on my 2012 VW Golf GTI. The MOST bus failure caused a complete shutdown of the infotainment system, affecting all multimedia functions. Car diagnostics revealed multiple control unit errors across the audio system network. The root cause was a faulty optical ring break in the MOST bus system, which required replacing the main control unit. This is actually a common failure point in these systems when the fiber optic connections degrade over time. The repair involved: Complete car electronics diagnostic scan, Testing all control units in the MOST network, Replacing the main multimedia control unit, Recoding and adaptation of the new unit, System-wide testing to verify all bus communications This was definitely not a simple fix as it required specialized diagnostic equipment and programming. The entire repair took about 6 hours since the technicians needed to verify all connected systems were communicating properly after the replacement. Even after getting everything fixed, we had to run multiple tests to ensure all control units were properly synchronized. These bus system failures often indicate deeper electrical architecture issues that need thorough investigation. My recommendation would be to have a full diagnostic scan done by a shop with VW-specific tools before attempting any repairs.

Thanks for the detailed repair info. This definitely matches the symptoms I was seeing with my system. Quick question, do you remember roughly how much you ended up paying for the full repair? Also curious if you experienced any other electrical gremlins since getting it fixed? My automotive protocol scan is showing similar MOST bus errors, so hoping the fix will be straightforward like yours.

Thanks for asking about the costs. Yes, I took my Golf to the dealer last month and the MOST bus fault was fully resolved. The total repair came to 1000€ which covered replacing one of the defective control units in the bus system. The car diagnostics confirmed the fix was successful, all audio system components are now communicating properly through the MOST bus network. Have not seen any electrical issues or control unit errors since the repair. The infotainment system works perfectly now. The initial automotive protocol scan was spot on in identifying the bus system failure. While it was not a cheap fix, having a properly functioning multimedia system again made it worthwhile. If your scan shows similar errors, you are likely looking at comparable repair costs for the control unit replacement.

Had my car diagnosed and repaired last week. Finally got everything sorted out! Just wanted to close the loop on this thread in case others run into similar issues. The repair cost was exactly as suggested, 980€ for the full fix including labor. The shop confirmed the data transmission fault in the MOST bus system and replaced the main control module. The fiber optics connection to the multimedia unit was also damaged and needed repair. The automotive protocol scan after the fix shows all systems communicating properly now. My infotainment, navigation and audio are working perfectly again. No other electrical problems have popped up since. Really appreciate the advice here, it helped me understand the issue and avoid getting overcharged. Having the background knowledge about the MOST bus system made discussions with the mechanic much more productive. For anyone else dealing with complete infotainment failure, definitely get the bus system checked first. A proper diagnostic scan will quickly reveal if you are dealing with the same control unit issue.