RS3 Door Lock System Failure: Security Chaos Alert

I had a very similar electrical issue on my 2021 S3 a few months back. With some experience working on basic car electrics, I first thought it was just the door switch, but it turned out more complex. The workshop found a faulty wiring harness where the contact signal from the door latch wasnt reaching the control module. The cables had worn through at a bend point near the door hinge. This affected the whole central locking system and security alerts. They replaced the damaged section of the wiring and tested all door switches to ensure proper contact signal. Total repair including diagnostic took about 2 hours and cost 95 Euro. The car has worked flawlessly since then. To help with your specific case, could you share: Does this happen with all doors or just one specific door? Can you hear any clicking sounds when using the key fob? Did this start suddenly or gradually get worse? Have you noticed any other electrical issues like window controls or mirror adjustments? With those details, I might be able to confirm if your issue matches what I experienced with my car.

Thanks for sharing your experience. My RS3 has 87702 KM and the issue started suddenly across all doors. Interestingly, I do hear a faint clicking from the main control module when using the key fob, but the door switches remain unresponsive. No other electrical issues with windows or mirrors so far. Your wiring harness situation sounds similar since my automatic locks are showing the same symptoms. I think the car sensor system needs a complete diagnostic check before any repair work starts. The car alarm sometimes triggers out of nowhere which seems related to the door switch malfunction. I will get it checked professionally since electrical issues can be tricky to diagnose correctly without proper testing equipment.

Thanks for those additional details. When my S3 had similar issues, I also noticed that clicking sound from the control module. In my case, even after fixing the harness, we discovered the door sensor needed recalibration, something I didnt mention in my first reply. The unusual car alarm triggers are a classic sign that the door contact signal is inconsistent. The system thinks the door is being tampered with when the sensor data is erratic. The fact that all your door switches are affected points more toward a central system issue rather than individual door sensors. For reference, after the initial harness repair I mentioned before, we had to go back because the automatic locks were still occasionally glitchy. The technician found that the main door switch module needed a firmware update to properly communicate with the door sensors. This second fix cost an additional 60 Euro but solved all remaining issues including those unusual alarm activations. Given your mileage and the sudden onset across all doors, Id suggest having them check both the wiring harness and the control module firmware. The symptoms are nearly identical to what my car exhibited before the complete fix. Let us know what the workshop finds, it would be helpful to confirm if your RS3 shows the same root cause as my S3.

Thanks for all the input. After checking the symptoms against what you described, I booked the car in for next week. The service advisor mentioned they will start with a full diagnostic of the electrical system and door sensors. They quoted around 150 Euro for initial testing and basic repairs if the automatic locks just need a module reset or firmware update. The unusual car alarm issue has gotten more frequent in the past few days. Sometimes it triggers even when the car is just sitting parked, which matches what you experienced with the faulty door contact signal. Hopefully, they can sort out both the door latch electrical issues and alarm system at the same time. I will update the thread once I get the final diagnosis. The detailed information about your similar wiring harness problem and sensor recalibration helps set realistic expectations for what might need fixing. Good to know these electrical issues can usually be resolved without major component replacements.