VW Arteon Won't Start After ECU Software Update

I had a similar starting issue with my 2020 VW Passat 2.0 TSI after routine maintenance. The symptoms matched exactly, cranking without firing up. The check engine light also appeared intermittently before the complete failure to start. Initially suspected ECU failure due to recent engine software updates, but the actual problem was much simpler. The battery cable connections had corroded and loosened, causing inconsistent power supply to the ECU. This created false readings and prevented proper engine management. The fix involved: Cleaning battery terminals and connectors, Replacing corroded cable ends, Retightening all ground connections, Resetting the engine fault codes, Verifying ECU communication While not a serious repair, poor battery connections can mimic ECU failure symptoms and trigger various engine fault warnings. The engine software and ECU were actually functioning correctly once proper power was restored. Recommend checking these basic electrical connections before pursuing complex diagnostic paths. Many starting issues after ECU updates trace back to power supply problems rather than actual software faults.

Thanks for sharing your experience with the Passat. Good to hear it was just corroded connections rather than a full ECU failure. Do you remember what the repair cost was? My Arteon has actually been back to the garage twice now. The fuel injection system was also checked but they found no issues there. Still having intermittent starting problems though, especially on cold mornings. Did you have any recurring issues after your initial fix?

Happy to report that after getting the battery cable connections properly fixed, I never experienced any engine control malfunction again. The total repair cost came to 155€, which covered cleaning, replacing the corroded parts, and resetting all engine fault codes. Unlike your situation with the fuel injection checks, my starting issues completely disappeared once the power supply was sorted. No more problems even during cold starts. The engine diagnostics showed everything running smoothly after the fix, with no error codes returning. If youre still getting intermittent starting problems, especially in cold weather, you might want to have them check for engine surge symptoms or other ECU communication issues. Sometimes what seems like a simple starting problem can mask deeper electrical gremlins in the system. My mechanic mentioned that engine fault warnings often pop up due to voltage fluctuations, but once the battery connections are properly secured, these generally clear up permanently. This relatively cheap fix saved me from unnecessarily replacing more expensive components.

After those helpful replies, I decided to take my Arteon back to the shop. They found a hairline crack in the wiring harness connector near the ECU, likely damaged during the previous software update work. This was causing intermittent connection issues, especially when the engine bay got cold and the materials contracted. The repair took about 3 hours and cost 280€, including: Replacement of the damaged wiring connector, Full system diagnostic scan, Reset of all engine fault codes, Test drive verification Been driving for 2 weeks now without any starting problems. The engine light hasnt returned and cold morning starts are working perfectly. Much relieved it wasnt a major ECU issue or expensive engine component failure. Thanks to everyone who shared their experiences. Sometimes these engine faults really come down to finding the right mechanic who can spot these small but critical issues.