Audi S5 Door Lock System Failure: Wiring Fix Alert

I had a very similar electrical issue with my 2018 Audi S4. The door sensor system completely failed, making both the central locking and keyless entry unusable. Based on my moderate experience with car electronics, I initially thought it was the door latch mechanism. After taking it to my regular workshop, they diagnosed a loose plug connection in the wiring harness between the door and frame. The contact signal was intermittent due to this faulty connection. The total repair cost was 95 Euro, which covered reconnecting and securing the plug, plus testing all door functions. The fix was relatively straightforward once properly diagnosed, but finding the exact location of the loose connection required professional diagnostic equipment. The symptoms you describe sound nearly identical to what I experienced. To provide more specific guidance, could you share: Whether this started suddenly or developed gradually, If you notice any unusual sounds when trying to lock/unlock, If the issue affects all doors equally, Whether the central locking works with the physical key This information would help determine if youre dealing with a similar wiring harness issue or potentially something else in the door sensor system.

Last serviced at 21088KM. Both the door switch and door latch were inspected during this service, with all electrical connections testing normal at that time. The issue started about 3 weeks after that service. The door sensor problem is definitely intermittent, sometimes the locking works for a few attempts before failing again. No unusual sounds present. The car alarm and security systems remain fully functional. I checked all fuses as suggested in the manual, but didnt find any obvious issues. The physical key still works normally in all doors.

Thanks for the additional details about the timing and symptoms. This actually mirrors my own experience with the S4 very closely. The intermittent nature of your door sensor issue, combined with the fact it started shortly after service, strongly suggests a wiring harness connection problem similar to what I encountered. The normal functioning of your physical key and alarm system further supports this theory, as a faulty contact signal typically wont affect these mechanical and separate electrical systems. In my case, the wire connections had worked loose gradually after the service, creating an inconsistent electrical contact. The repair process involved: Full diagnostic scan of the door sensor network, Testing the contact signal at multiple points, Inspecting the wiring harness for loose connections, Reseating and securing all relevant connectors Since your symptoms are nearly identical, I suggest having the shop specifically check the wiring harness connections between the door and frame. The intermittent electrical issue could be caused by movement of the harness when opening/closing the door. The repair should be relatively affordable, my fix was around 95 Euro plus diagnostic fees. Much better than replacing entire components unnecessarily.

Thanks for the detailed response. Given your experiences with a similar door sensor problem, I feel more confident that this could indeed be wiring harness related rather than a complete door latch failure. The fact that both of our issues started after routine service is particularly telling. My intermittent electrical issue does sound remarkably similar to your case, especially since the car alarm and physical key functions remain unaffected. The gradual connection deterioration pattern matches exactly what Im experiencing. Ill definitely have the shop focus on checking the wiring harness connections first, particularly around the door frame area where movement could cause intermittent contact. Your repair cost reference of 95 Euro gives me a good baseline for what to expect, which is much more reasonable than I initially feared. Really appreciate you sharing your experience, it helped narrow down the likely cause and saved me from potentially unnecessary parts replacement. Ill make sure to request a full diagnostic scan of the door sensor system when I take it in.