Audi S7's Start-Stop Failure Causes Engine Shutdowns

I had a similar issue with my 2019 Audi S5. The main problem turned out to be a failing car battery that was causing the start-stop system to malfunction. The battery issue was affecting multiple systems, triggering warning lights and creating irregular idle stop behavior. The automatic restart system relies heavily on battery performance. When the battery starts degrading, it cant provide consistent power for the start-stop functions. In my case, the battery testing showed it was operating at less than 60% capacity. The solution required: Complete battery system diagnosis, Replacement of the main battery, Recalibration of the start-stop system, Reset of the engine control unit This was a serious repair as the failing battery was causing strain on other electrical components. The symptoms you describe match exactly what I experienced, unusual shutoffs, warning lights, and the start-stop system becoming unreliable. A specialized Audi workshop is recommended since they have the proper diagnostic tools to check the entire start-stop system. The generic scanners at regular shops often cant fully diagnose these specific issues.

Thanks for sharing your experience with the battery and start-stop system issues. The problems you described match my situation perfectly. I plan to have the battery performance tested first since this seems like the most logical starting point. Would you mind sharing what the total repair cost was for your hybrid vehicle fix? Also curious if youve had any recurring issues with the automatic restart system since the repair was completed?

Thanks for asking about the follow-up. Since having the battery replaced and system recalibrated, my Audi S5 has been running perfectly with no recurring issues. The start-stop system works flawlessly now, and I havent seen any warning lights or experienced engine stalling. The total repair came to 290 Euro, which covered the battery replacement, diagnostics, and system recalibration. It was definitely worth addressing the battery issue early, as a heavily discharged battery can potentially damage other electrical components over time. The eco mode and automatic restart features all function normally now, just like when the car was new. Getting this fixed at a specialized shop was key, as they properly diagnosed the failing battery as the root cause rather than just treating the symptoms.

Just got back from the shop and wanted to share my experience. Had the battery tested and, sure enough, it was operating at barely 50% capacity. The starter motor was also showing signs of strain from the weak battery. The repair cost came to 310 Euro total, slightly more than yours but included a full system check. The mechanic also cleaned the battery connections and updated some control modules related to the idle stop function. After a week of driving, the start-stop system works perfectly now. No more sudden engine stalling or warning lights. The eco mode engages smoothly, and the automatic restart is quick and reliable. Really glad I followed your advice about checking the battery first instead of replacing more expensive components.