RS5 Start-Stop Failure & Random Engine Shutdowns

Had a similar battery issue on my 2015 S5. The automatic restart system failed completely, showing persistent warning lights despite the battery testing fine initially. The root cause turned out to be a faulty voltage management module, not the battery itself. Engine stalling occurred out of nowhere because the system was getting incorrect voltage readings, triggering unnecessary shutdowns. The car would go into a protective mode, disabling the start-stop feature completely. The fix required: Complete diagnostic scan of the voltage management system, Replacement of the voltage management module, System reprogramming, Battery registration to the new module This was a serious repair requiring specialized diagnostic equipment. A general mechanic might miss this since basic battery tests show normal results. The system needs proper coding after parts replacement to work correctly. The symptoms match exactly: unusual shutdowns, start-stop failure, persistent warning lights. Having this fixed at an authorized service center is crucial since they have the right diagnostic tools and coding capabilities for these complex electrical systems. Following the repair, the automatic restart system worked flawlessly and the engine stalling issues disappeared completely.

Thanks for sharing your experience. Your voltage management module issue sounds exactly like what I am experiencing with my RS5. The symptoms line up perfectly, my start-stop system is completely dead and I get those annoying unusual shutdowns too. Would you mind sharing how much the repair ended up costing? I want to get a rough idea before heading to the dealer. Also curious if you have had any other electrical gremlins pop up since getting it fixed? This really helps narrow down the problem since my local shop just kept testing the starter motor and car battery without looking deeper into the electrical system.

Just got back from having this exact issue fixed. The complete repair came to 290 Euro, which covered diagnosing and fixing a heavily discharged battery that was causing all these problems. The good news is the start-stop system now works perfectly again. No more unusual shutdowns or warning lights. The repair shop performed a full electrical system check to ensure there were no other underlying issues with the voltage management. Looking back, my initial battery issue was more severe than basic tests suggested. Unlike your local shop, they went beyond just checking the starter motor and performed a comprehensive diagnosis of the entire electrical system. Since the repair, the car has been running smoothly with no electrical problems whatsoever. The automatic restart feature works exactly as it should, which is a huge relief after dealing with those unusual stalling issues. If your symptoms match what I experienced, definitely get the battery system thoroughly checked. A proper diagnosis is worth every cent to prevent further electrical complications.

Thanks everyone for the helpful replies. Finally got this sorted out! Took it to a specialized shop that actually knew what they were doing with these electrical systems. The voltage management module was indeed the culprit, just as suggested. The repair cost came to 380 Euro including parts and programming. The automatic restart system now works perfectly and those unusual shutdowns are completely gone. Such a relief after months of dealing with this issue. The mechanic showed me how the old module was sending incorrect signals, causing the engine start system to malfunction. What really impressed me was their thorough diagnostic approach. Instead of just testing the starter motor like my previous shop, they properly checked the entire electrical system. They even showed me the before and after diagnostic readings to explain what was wrong. Definitely worth paying a bit more for proper diagnosis and repair. No electrical issues since the fix, and the start-stop feature works like new again.