Audi S4 Auto Start-Stop Failure Causes Random Shutdowns

Had similar issues with a 2017 Audi S5. The start-stop system began malfunctioning, causing unusual engine stalling and difficulty starting. The car battery was heavily discharged, triggering multiple warning lights and error codes. The root cause was a failing voltage management system that incorrectly regulated power between the main car battery and the secondary battery that supports the start-stop system. This created a cascade effect, damaging both batteries and straining the alternator. The fix required: Replacing both batteries, Installing a new voltage management module, Recalibrating the start-stop system, Clearing all stored error codes This was a serious repair requiring specialized diagnostic equipment. The voltage management system in these models needs proper testing, as generic diagnostics often miss the underlying issue. Watch out for shops attempting quick fixes by just replacing the main battery, as this wont solve the core problem. Signs that indicated severity: Multiple warning lights, Unusual engine stalling, Start-stop system deactivation, Recurring battery drain even after charging Recommend finding a shop with experience in modern start-stop systems and Audi electrical diagnostics to avoid repeated repairs.

Had similar issues with a 2017 Audi S5. The start-stop system began malfunctioning, causing unusual engine stalling and difficulty starting. The car battery was heavily discharged, triggering multiple warning lights and error codes. The root cause was a failing voltage management system that incorrectly regulated power between the main car battery and the secondary battery that supports the start-stop system. This created a cascade effect, damaging both batteries and straining the alternator. The fix required: Replacing both batteries, Installing a new voltage management module, Recalibrating the start-stop system, Clearing all stored error codes This was a serious repair requiring specialized diagnostic equipment. The voltage management system in these models needs proper testing, as generic diagnostics often miss the underlying issue. Watch out for shops attempting quick fixes by just replacing the main battery, as this wont solve the core problem. Signs that indicated severity: Multiple warning lights, Unusual engine stalling, Start-stop system deactivation, Recurring battery drain even after charging Recommend finding a shop with experience in modern start-stop systems and Audi electrical diagnostics to avoid repeated repairs.

Had similar issues with a 2017 Audi S5. The start-stop system began malfunctioning, causing unusual engine stalling and difficulty starting. The car battery was heavily discharged, triggering multiple warning lights and error codes. The root cause was a failing voltage management system that incorrectly regulated power between the main car battery and the secondary battery that supports the start-stop system. This created a cascade effect, damaging both batteries and straining the alternator. The fix required: Replacing both batteries, Installing a new voltage management module, Recalibrating the start-stop system, Clearing all stored error codes This was a serious repair requiring specialized diagnostic equipment. The voltage management system in these models needs proper testing, as generic diagnostics often miss the underlying issue. Watch out for shops attempting quick fixes by just replacing the main battery, as this wont solve the core problem. Signs that indicated severity: Multiple warning lights, Unusual engine stalling, Start-stop system deactivation, Recurring battery drain even after charging Recommend finding a shop with experience in modern start-stop systems and Audi electrical diagnostics to avoid repeated repairs.

Thanks for sharing your experience with the S5. I had a very similar issue on my S4 last year. The automatic restart system kept failing and the starter motor would struggle, especially after the engine was warm. After replacing both batteries initially, the problem came back within weeks. The voltage management module turned out to be the real culprit, just like in your case. Engine stalling became more frequent until I finally got it properly diagnosed by a specialist. They found the hybrid vehicle start-stop system was getting wrong signals from the faulty module. Did you remember roughly how much the complete fix cost you? Also curious if youve had any electrical issues since the repair was done? My car has been running fine for 8 months now but always good to know what to watch out for.

Thanks for sharing your experience with the S5. I had a very similar issue on my S4 last year. The automatic restart system kept failing and the starter motor would struggle, especially after the engine was warm. After replacing both batteries initially, the problem came back within weeks. The voltage management module turned out to be the real culprit, just like in your case. Engine stalling became more frequent until I finally got it properly diagnosed by a specialist. They found the hybrid vehicle start-stop system was getting wrong signals from the faulty module. Did you remember roughly how much the complete fix cost you? Also curious if youve had any electrical issues since the repair was done? My car has been running fine for 8 months now but always good to know what to watch out for.

Thanks for sharing your experience with the S5. I had a very similar issue on my S4 last year. The automatic restart system kept failing and the starter motor would struggle, especially after the engine was warm. After replacing both batteries initially, the problem came back within weeks. The voltage management module turned out to be the real culprit, just like in your case. Engine stalling became more frequent until I finally got it properly diagnosed by a specialist. They found the hybrid vehicle start-stop system was getting wrong signals from the faulty module. Did you remember roughly how much the complete fix cost you? Also curious if youve had any electrical issues since the repair was done? My car has been running fine for 8 months now but always good to know what to watch out for.

Happy to report the complete repair solved all electrical problems with my S5. The starter motor works flawlessly now, and the start-stop system operates as designed with no engine stalling or warning lights. I paid 290 Euro for the battery replacement, which turned out to be heavily discharged and damaged beyond repair. The voltage management fix made a huge difference, no more unusual shutdowns or electrical gremlins. The car runs perfectly in both normal and eco mode settings. Having a specialist diagnose and repair it properly was worth every cent, rather than just trying quick fixes that dont address the root cause. After 2 years since the repair, the start-stop system still works like new with no voltage issues or battery problems. Just make sure to run the car regularly to keep the battery charged and everything should stay reliable.

Happy to report the complete repair solved all electrical problems with my S5. The starter motor works flawlessly now, and the start-stop system operates as designed with no engine stalling or warning lights. I paid 290 Euro for the battery replacement, which turned out to be heavily discharged and damaged beyond repair. The voltage management fix made a huge difference, no more unusual shutdowns or electrical gremlins. The car runs perfectly in both normal and eco mode settings. Having a specialist diagnose and repair it properly was worth every cent, rather than just trying quick fixes that dont address the root cause. After 2 years since the repair, the start-stop system still works like new with no voltage issues or battery problems. Just make sure to run the car regularly to keep the battery charged and everything should stay reliable.

Happy to report the complete repair solved all electrical problems with my S5. The starter motor works flawlessly now, and the start-stop system operates as designed with no engine stalling or warning lights. I paid 290 Euro for the battery replacement, which turned out to be heavily discharged and damaged beyond repair. The voltage management fix made a huge difference, no more unusual shutdowns or electrical gremlins. The car runs perfectly in both normal and eco mode settings. Having a specialist diagnose and repair it properly was worth every cent, rather than just trying quick fixes that dont address the root cause. After 2 years since the repair, the start-stop system still works like new with no voltage issues or battery problems. Just make sure to run the car regularly to keep the battery charged and everything should stay reliable.

Thanks to everyone for the helpful replies. After getting multiple estimates, I took my S4 to a certified shop specializing in German vehicles. The diagnosis confirmed the voltage management module failure affecting the automatic restart system. The total repair came to 1850 Euro including: New voltage management module, Both batteries replaced, System recalibration, Full diagnostic scan The idle stop feature now works perfectly and no more unusual engine stalling. The eco mode settings all function normally again. The specialist explained the importance of the voltage management system in modern cars with start-stop technology. Been driving for 3 months now without any electrical issues. The engine start is smooth and consistent. Really glad I went with a proper fix rather than trying cheaper alternatives that wouldnt have solved the core problem. For anyone facing similar issues, dont waste time with basic repairs. Get it properly diagnosed by someone who knows these hybrid vehicle systems. The extra cost upfront saves money in the long run.

Thanks to everyone for the helpful replies. After getting multiple estimates, I took my S4 to a certified shop specializing in German vehicles. The diagnosis confirmed the voltage management module failure affecting the automatic restart system. The total repair came to 1850 Euro including: New voltage management module, Both batteries replaced, System recalibration, Full diagnostic scan The idle stop feature now works perfectly and no more unusual engine stalling. The eco mode settings all function normally again. The specialist explained the importance of the voltage management system in modern cars with start-stop technology. Been driving for 3 months now without any electrical issues. The engine start is smooth and consistent. Really glad I went with a proper fix rather than trying cheaper alternatives that wouldnt have solved the core problem. For anyone facing similar issues, dont waste time with basic repairs. Get it properly diagnosed by someone who knows these hybrid vehicle systems. The extra cost upfront saves money in the long run.

Thanks to everyone for the helpful replies. After getting multiple estimates, I took my S4 to a certified shop specializing in German vehicles. The diagnosis confirmed the voltage management module failure affecting the automatic restart system. The total repair came to 1850 Euro including: New voltage management module, Both batteries replaced, System recalibration, Full diagnostic scan The idle stop feature now works perfectly and no more unusual engine stalling. The eco mode settings all function normally again. The specialist explained the importance of the voltage management system in modern cars with start-stop technology. Been driving for 3 months now without any electrical issues. The engine start is smooth and consistent. Really glad I went with a proper fix rather than trying cheaper alternatives that wouldnt have solved the core problem. For anyone facing similar issues, dont waste time with basic repairs. Get it properly diagnosed by someone who knows these hybrid vehicle systems. The extra cost upfront saves money in the long run.