Subaru Audio Dead: MOST Bus Network Failure Warning

I had a very similar issue with my 2012 Subaru Trezia last year (some experience with car electronics). The symptoms match exactly what you describe, complete failure of the infotainment system with multiple functions affected at once. After checking the bus network diagnostics, it turned out to be a faulty control unit that was disrupting the entire MOST bus data transmission system. Initially thought it might just be loose connections or fiber optic cable damage, but the workshop diagnosed a defective main control unit in the bus system. The repair required replacing the control unit and reconfiguring the whole network to restore proper communication between components. Total cost came to 1000€ including parts, labor and system configuration. Before giving more specific advice, could you share: Complete error codes from diagnostics, whether you see any flickering in other electronic systems, if the issue started suddenly or developed gradually, if any aftermarket equipment was installed recently This information would help determine if your case is similar to what I experienced with the MOST bus failure.

Last service was at 165000 KM. After running car diagnostics through my OBD scanner yesterday, I found multiple communication errors in the automotive protocol logs. The control unit seems to throw similar fault codes as described. The fiber optic ring in my car electronics is definitely disrupted based on the error pattern. My bus network shows the same symptoms with flickering displays and complete audio failure. Will try checking all connections first before replacing any parts, since the issue started after hitting a deep pothole.

Thanks for the additional details. Since I had almost identical symptoms with my Trezia, I can confirm this matches the typical pattern of MOST bus network issues. The timing with the pothole impact is telling, in fiber optics networks, physical shocks can sometimes damage connections or loosen components. Before replacing the control unit like I had to, definitely check the fiber optic connections first. The automotive protocol errors you found through car diagnostics are very similar to what my system showed, but in my case, the loose connections check did not solve it. A few tips from my experience: Inspect all visible fiber optic ring connection points for proper seating, Pay special attention to areas near where the impact was felt, Have the workshop run a complete MOST bus signal test before replacing parts Unlike my situation where the control unit was actually faulty, you might get lucky with just reseating connections given the clear connection to the pothole incident. If simple fixes dont work, prepare for control unit replacement costs around 1000€ based on my repair bill. Keep us posted on what you find, this could help others with similar car electronics issues.

Appreciate all the detailed feedback. Just got back from checking the fiber optic connections in my car electronics as suggested. You were right about the impact damage, found a partially disconnected MOST bus connector right behind the head unit. The audio system came back to life after carefully reseating all connections in the bus network. Even the flickering display issues are gone now. The control unit is reading normally again with no more error codes showing up in the diagnostic scan. Saved myself a costly repair by troubleshooting the bus system connections first. Total cost was just 50€ for the diagnostic scan. Really glad it wasnt a complete control unit failure like in your case. Going to add some extra padding around those connectors to prevent future damage from road impacts. Will definitely keep this solution in mind if similar symptoms pop up again. The fiber optic network is clearly more sensitive to physical shocks than traditional wiring.