RSQ3 Engine Stalling Due to Start-Stop System Failure

I had a very similar issue with my 2020 SQ3 last winter. As someone with moderate experience working on cars, I initially thought it was just the idle stop system acting up. The main issue turned out to be a heavily discharged car battery that could no longer maintain proper voltage. This affected the start-stop system performance and caused unusual engine shutdowns, especially when the hybrid vehicle systems demanded more power. The workshop diagnosed it using battery testing equipment and found the battery was only holding about 40% of its original capacity. The repair involved: Complete battery diagnostic test, Replacement with a new AGM battery, Recalibration of the start-stop system, Reset of the engine control unit Total cost was 290 Euro for parts and labor. Since the repair, the engine start sequence works flawlessly and no more unexpected shutdowns occur. Could you share: How old is your current battery? Does the issue happen more frequently in cold weather? Are you using any aftermarket accessories that might drain the battery? Have you noticed any other electrical issues? This information would help determine if your case is similar to what I experienced.

Latest service was at 144000 KM about 2 weeks ago. Thanks for sharing your experience. After reading your response, I checked my vehicle log and found the original battery has never been replaced since 2022. The issues do occur more in cold weather, and I have a dashcam permanently connected to the battery. The eco mode and idle stop features worked perfectly until recently. Now the car battery warning occasionally flashes before engine stalling occurs. Makes sense that this could be battery-related since the problems started appearing after I installed the dashcam. Will get the battery tested first thing at the workshop. But based on the symptoms you described, it sounds very similar to my situation. Quite helpful to know the repair costs. 290 Euro seems reasonable if it solves these engine stalling issues completely. Will update once I get it checked.

Thanks for the additional details. The dashcam installation definitely sounds like it contributed to the battery issue. With the original 2022 battery still in place and a constantly powered accessory, this matches the battery drain pattern I experienced. A few points from my repair experience that might help: The workshop found that modern start-stop systems are quite sensitive to battery voltage fluctuations, The automatic restart function is usually the first to show symptoms of a weak battery, Cold weather significantly impacts battery performance, especially with extra power draws The total repair cost might vary slightly since parts prices have changed, but the 290 Euro I paid included: High-performance AGM battery suitable for start-stop systems, Battery monitoring system reset, System diagnostic scan After the repair, make sure they properly configure the dashcam with a voltage cutoff device to prevent future battery issues. This prevents the accessory from draining the battery below critical levels. Our cases sound nearly identical, and the battery warning light you mentioned further confirms this diagnosis. The eco mode and idle stop features should return to normal operation once the battery is replaced.

The symptoms from my RSQ3 match your experience exactly. After looking at all the details, seems my original battery from 2022 plus the constant drain from the dashcam are the likely culprits. The starter motor issues and engine stalling get worse in cold weather, just as you described. The automatic restart feature of the idle stop system worked fine before the dashcam installation, which explains why these problems developed recently. Good point about getting a voltage cutoff device for the dashcam. Will definitely have that installed along with the new battery to prevent future issues. The 290 Euro repair cost is reasonable considering it includes the AGM battery, system resets, and diagnostic work. I made an appointment with the workshop for next week. Will have them test the battery first to confirm, but based on the battery warning light and matching symptoms with your case, I expect to need the same fix. The start-stop system problems and engine stalling should resolve once the battery is replaced and properly set up. Thanks for sharing such detailed information about your repair experience. Made me feel much more confident about the likely cause and solution.