Audi Q5 Hybrid Stalling Issues & Start-Stop Failures

As a hobby mechanic with some hands-on experience, I had a very similar issue with my 2020 Audi Q4 hybrid. The symptoms matched exactly what you describe, unusual stalling and start-stop system failures. The root cause was a failing car battery that was heavily discharged. The starter motor system needs a consistently strong power supply to function properly, especially in hybrid vehicles where the start-stop system is activated frequently. The repair process involved: Complete battery diagnostic test, Checking the start-stop system components, Testing the starter motor functionality, Replacing the main battery Total repair cost was 290 Euro and the work took about 2 hours. Since the fix, the engine start functions have worked flawlessly and the start-stop system operates as intended. To provide more specific guidance for your case, could you share: Current battery age, Warning light patterns, Error codes from the diagnostic, Recent changes in driving patterns This information would help determine if your issue follows the same pattern as mine or if theres something else at play with your Q5.

Thanks for the detailed explanation about the battery issue and engine stalling problems. My Q5 just had its last service at 170503 KM where they checked the start-stop system thoroughly and found no faults. However, the idle stop function started acting up shortly after. The error codes point to a different problem than yours, the main control unit for the hybrid system appears to be the culprit, not the battery. Running diagnostics showed the eco mode also behaves erratically when these faults occur. Getting it checked again next week as the previous fix didnt resolve the stalling issue completely.

Thanks for the follow-up about your Q5 hybrid issues. This is quite interesting since my Q4 actually showed similar symptoms after the initial battery fix, unusual faults in the hybrid control module. The start-stop system problems were indeed just a symptom of a larger issue with the main control unit. After the battery replacement didnt fully solve the problem, the workshop found corrupt software in the hybrid management system causing the engine stalling and eco mode glitches. The actual fix required: Software update of the hybrid control module, Recalibration of the start-stop system, Reset of the eco mode parameters, Full system diagnostic reset Total repair time was around 4 hours and cost 450 Euro. This completely resolved both the engine stalling and erratic eco mode behavior. Since your error codes specifically point to the control unit, you might want to ask the workshop about potential software updates. These hybrid systems often need recalibration when showing multiple related faults.

Thanks for sharing those details about the software update fix. Just called the workshop and they confirmed similar cases where the hybrid control module needed a complete system update. The automatic restart system definitely seems more complex than I initially thought. My car is showing the exact same symptoms you described, engine stalling when the eco mode engages and inconsistent start-stop system behavior. The error codes from my latest scan match the ones you mentioned for the control unit issues. Will bring this up during next weeks appointment. The 4-hour repair time fits my schedule, and 450 Euro seems reasonable for a full hybrid system recalibration. Really hope this resolves both the stalling and eco mode problems permanently, as the previous quick fixes clearly werent enough. Just wondering, after your repair, did you notice any changes in how the start-stop system behaves? Mine feels a bit sluggish even when working, so Im curious if the software update improved the overall responsiveness too.