Audi RS4 Random Shutdowns: Idle Stop System Failure Fix

Had the same issue on my Audi S5 (2012) last winter. The symptoms matched exactly, unusual engine stalling and start-stop system malfunction warnings. The root cause was a failing car battery combined with a faulty voltage management system. The battery could not maintain proper voltage during start-stop cycles, causing the system to malfunction and eventually leading to complete engine shutdowns. Required fixes: Full battery diagnostic test, Replacement of original battery with AGM type, Reset of battery management system, Clear fault codes This was a serious repair that needed immediate attention. A deteriorating battery can damage other electrical components and leave you stranded. The eco mode and start-stop system are particularly sensitive to battery health. The symptoms you describe strongly suggest your RS4 has similar battery/electrical issues. Would recommend: 1. Get battery load tested first 2. Check alternator output 3. Have voltage drops tested across major circuits 4. Scan for detailed fault codes beyond basic OBD Continuing to drive with these symptoms risks damaging the start-stop system and other electrical components. A proper diagnosis at an Audi specialist should be your next step.

Had the same issue on my Audi S5 (2012) last winter. The symptoms matched exactly, unusual engine stalling and start-stop system malfunction warnings. The root cause was a failing car battery combined with a faulty voltage management system. The battery could not maintain proper voltage during start-stop cycles, causing the system to malfunction and eventually leading to complete engine shutdowns. Required fixes: Full battery diagnostic test, Replacement of original battery with AGM type, Reset of battery management system, Clear fault codes This was a serious repair that needed immediate attention. A deteriorating battery can damage other electrical components and leave you stranded. The eco mode and start-stop system are particularly sensitive to battery health. The symptoms you describe strongly suggest your RS4 has similar battery/electrical issues. Would recommend: 1. Get battery load tested first 2. Check alternator output 3. Have voltage drops tested across major circuits 4. Scan for detailed fault codes beyond basic OBD Continuing to drive with these symptoms risks damaging the start-stop system and other electrical components. A proper diagnosis at an Audi specialist should be your next step.

Had the same issue on my Audi S5 (2012) last winter. The symptoms matched exactly, unusual engine stalling and start-stop system malfunction warnings. The root cause was a failing car battery combined with a faulty voltage management system. The battery could not maintain proper voltage during start-stop cycles, causing the system to malfunction and eventually leading to complete engine shutdowns. Required fixes: Full battery diagnostic test, Replacement of original battery with AGM type, Reset of battery management system, Clear fault codes This was a serious repair that needed immediate attention. A deteriorating battery can damage other electrical components and leave you stranded. The eco mode and start-stop system are particularly sensitive to battery health. The symptoms you describe strongly suggest your RS4 has similar battery/electrical issues. Would recommend: 1. Get battery load tested first 2. Check alternator output 3. Have voltage drops tested across major circuits 4. Scan for detailed fault codes beyond basic OBD Continuing to drive with these symptoms risks damaging the start-stop system and other electrical components. A proper diagnosis at an Audi specialist should be your next step.

Thanks for the detailed writeup. Those symptoms indeed match what I experienced. The automatic restart failures were super annoying and made me nervous about getting stranded somewhere. The biggest problem was the starter motor getting extra stress from the malfunctioning start-stop system. Just want to confirm, did you also get the starter checked during your repair? My mechanic suggests replacing it preventively but I am unsure if that is really needed. Quick question, do you remember roughly what was the total cost for your fix? And have you had any issues since getting it sorted out? Just trying to get an idea of what I might be looking at cost-wise and if the fix actually solved everything long-term.

Thanks for the detailed writeup. Those symptoms indeed match what I experienced. The automatic restart failures were super annoying and made me nervous about getting stranded somewhere. The biggest problem was the starter motor getting extra stress from the malfunctioning start-stop system. Just want to confirm, did you also get the starter checked during your repair? My mechanic suggests replacing it preventively but I am unsure if that is really needed. Quick question, do you remember roughly what was the total cost for your fix? And have you had any issues since getting it sorted out? Just trying to get an idea of what I might be looking at cost-wise and if the fix actually solved everything long-term.

Thanks for the detailed writeup. Those symptoms indeed match what I experienced. The automatic restart failures were super annoying and made me nervous about getting stranded somewhere. The biggest problem was the starter motor getting extra stress from the malfunctioning start-stop system. Just want to confirm, did you also get the starter checked during your repair? My mechanic suggests replacing it preventively but I am unsure if that is really needed. Quick question, do you remember roughly what was the total cost for your fix? And have you had any issues since getting it sorted out? Just trying to get an idea of what I might be looking at cost-wise and if the fix actually solved everything long-term.

Just got everything sorted last week actually. The total repair came to 290 Euro which covered replacing the heavily discharged battery and resetting all systems. Like your case, my automatic restart was failing constantly, but since the new battery installation, the idle stop feature works flawlessly again. The engine start is smooth every time, and the eco mode functions exactly as it should. I skipped the starter motor replacement since diagnostic tests showed it was still in good condition. A year later, no regrets about that decision, everything works perfectly. My mechanic explained that while the faulty car battery did put extra strain on the starter, catching the issue early prevented any permanent damage. The fix completely resolved all the unusual shutdowns and warning lights. The automatic restart system now engages properly at traffic lights, and I have not experienced a single issue since the repair. Just make sure you get a high-quality AGM battery installed, it makes a huge difference for these start-stop systems.

Just got everything sorted last week actually. The total repair came to 290 Euro which covered replacing the heavily discharged battery and resetting all systems. Like your case, my automatic restart was failing constantly, but since the new battery installation, the idle stop feature works flawlessly again. The engine start is smooth every time, and the eco mode functions exactly as it should. I skipped the starter motor replacement since diagnostic tests showed it was still in good condition. A year later, no regrets about that decision, everything works perfectly. My mechanic explained that while the faulty car battery did put extra strain on the starter, catching the issue early prevented any permanent damage. The fix completely resolved all the unusual shutdowns and warning lights. The automatic restart system now engages properly at traffic lights, and I have not experienced a single issue since the repair. Just make sure you get a high-quality AGM battery installed, it makes a huge difference for these start-stop systems.

Just got everything sorted last week actually. The total repair came to 290 Euro which covered replacing the heavily discharged battery and resetting all systems. Like your case, my automatic restart was failing constantly, but since the new battery installation, the idle stop feature works flawlessly again. The engine start is smooth every time, and the eco mode functions exactly as it should. I skipped the starter motor replacement since diagnostic tests showed it was still in good condition. A year later, no regrets about that decision, everything works perfectly. My mechanic explained that while the faulty car battery did put extra strain on the starter, catching the issue early prevented any permanent damage. The fix completely resolved all the unusual shutdowns and warning lights. The automatic restart system now engages properly at traffic lights, and I have not experienced a single issue since the repair. Just make sure you get a high-quality AGM battery installed, it makes a huge difference for these start-stop systems.

Thanks for the advice. Finally got this sorted out! After reading the suggestions here, I took the car to a new specialist shop. The diagnostic confirmed a failing battery was causing the idle stop malfunctions. The voltage was dropping too low during automatic restart attempts. The mechanic found the original battery was severely degraded and the voltage management system needed recalibration. They installed a new AGM battery, reset all the systems, and cleared the fault codes. The total bill was 320 Euro, definitely worth it to fix those unusual shutdowns. Been driving for two weeks now without any issues. The start-stop system works perfectly again and no more warning lights. Really glad I caught this early before it caused problems with other electrical components. Props to this forum for steering me in the right direction. Would have wasted time and money chasing other problems without the battery advice.

Thanks for the advice. Finally got this sorted out! After reading the suggestions here, I took the car to a new specialist shop. The diagnostic confirmed a failing battery was causing the idle stop malfunctions. The voltage was dropping too low during automatic restart attempts. The mechanic found the original battery was severely degraded and the voltage management system needed recalibration. They installed a new AGM battery, reset all the systems, and cleared the fault codes. The total bill was 320 Euro, definitely worth it to fix those unusual shutdowns. Been driving for two weeks now without any issues. The start-stop system works perfectly again and no more warning lights. Really glad I caught this early before it caused problems with other electrical components. Props to this forum for steering me in the right direction. Would have wasted time and money chasing other problems without the battery advice.

Thanks for the advice. Finally got this sorted out! After reading the suggestions here, I took the car to a new specialist shop. The diagnostic confirmed a failing battery was causing the idle stop malfunctions. The voltage was dropping too low during automatic restart attempts. The mechanic found the original battery was severely degraded and the voltage management system needed recalibration. They installed a new AGM battery, reset all the systems, and cleared the fault codes. The total bill was 320 Euro, definitely worth it to fix those unusual shutdowns. Been driving for two weeks now without any issues. The start-stop system works perfectly again and no more warning lights. Really glad I caught this early before it caused problems with other electrical components. Props to this forum for steering me in the right direction. Would have wasted time and money chasing other problems without the battery advice.