Audi Q2's MOST Bus Failure Kills All Entertainment

As someone with some experience in car electronics, I faced an identical issue with my 2018 Audi Q3. The symptoms matched exactly, complete infotainment failure and multiple error messages from the control unit. The root cause was indeed related to the bus system. After diagnostics, the workshop found a defective control unit that was disrupting the MOST bus network. These optical bus networks are quite sensitive, and when one component fails, it can affect the entire entertainment system. The repair involved: 1. Full diagnostic scan of the car electronics 2. Testing all nodes in the bus network 3. Replacing the faulty control unit 4. Recoding and adapting the new unit Total cost was 1000 Euro, including parts and labor. The repair took about 4 hours, but the car was perfect afterward with all systems working normally. To help further with your specific case: Have you scanned for error codes? Did this start suddenly or gradually? Are there any other electrical issues besides infotainment? Have you had any recent work done on the electrical systems? These details would help determine if your Q2 is experiencing the same bus system fault I encountered.

Thanks for your response about the MOST bus issue. After my last service at 107468 KM, the workshop actually checked the error codes and they pointed to a damaged fiber optic cable in the automotive protocol system. The control unit kept showing the same errors you mentioned, but in my case, the entire bus system was still partially working, as the phone connection stayed active. The technician found signs of rodent damage to the cable harness, which had compromised the car electronics. Unlike your situation, replacing the control unit alone would not have fixed my problem since the physical connection was broken. Currently waiting for parts, but the estimated repair costs are around 600 Euro.

Thanks for the update on your Q2's situation. The rodent damage explains a lot, this is actually quite different from my case where the control unit was the culprit. Data transmission through fiber optics is extremely sensitive to physical damage, which explains why your phone connection still worked while other systems failed. The 600 Euro repair quote sounds reasonable since they need to replace the damaged fiber optic cable sections. The tricky part with these repairs is ensuring perfect alignment during installation, even a slight misalignment in the optical bus system can cause communication issues. The partial functionality you mentioned with the phone actually helps confirm it is cable-specific rather than a system-wide failure like I had. When the control unit fails, it usually takes down all communication. Make sure the workshop also checks for additional damage while they are in there. Rodents rarely stop at just one spot, and preventive measures might be worth considering to protect the car electronics from future attacks. Will you let us know how the repair goes once the parts arrive? It would be helpful to know if replacing just the damaged sections fully resolves all the infotainment issues.

Yes, I will definitely update once the repair is completed. The workshop confirmed they will do a thorough inspection of the entire wiring harness while replacing the damaged sections. The car diagnostics showed the issue is isolated to that specific area, but better safe than sorry with rodent damage. Interesting point about the data transmission sensitivity, that explains why some functions stayed operational while others failed completely. They mentioned they will use specialized testing equipment to verify the optical bus network integrity after the repair. The parts should arrive next week. The control unit readings suggest no other damage to the core systems, so hoping the 600 Euro repair will fully resolve the infotainment issues. Will post the results here for others who might face similar automotive protocol problems in the future. Definitely planning to add some rodent protection measures while they have everything opened up. The car electronics are too expensive to risk another incident like this.