Audi SQ8 Central Locking System Failure Fix Guide

I had a similar issue with my 2019 Q8 last summer and can share my experience with fixing the central locking system. The key fob stopped communicating with the car security system completely, no response when pressing any buttons. The car computer showed the same error message about the door locks that you described. After some basic troubleshooting (checking key fob battery, trying the spare key), I took it to my regular workshop. They diagnosed a faulty wiring connection between the central locking control unit and the car computer. The cable had become loose over time, causing the entire system to fail. The repair was straightforward, they had to reconnect and secure the cables properly. Total cost was 95 Euro for labor and checking all connections in the security system. To help further with your specific case: Could you share if you noticed any warning signs before the complete failure? Also, does your spare key fob work, and have you already checked the key fob battery? This information would help determine if you are dealing with the same root cause. The central locking issue can be frustrating, but its usually a relatively simple fix once properly diagnosed.

Thanks for the detailed response. My mileage is 125162 KM and I had my last service 2 months ago. Actually the spare key fob is also not working, and I already replaced both batteries. The car alarm still functions normally when I manually lock with the physical key, but the keyless entry system is completely dead. No response at all from either key fob. When I plug in the diagnostic tool, it shows a fault code pointing to the fuse box area. The workshop said they need to check if its a blown fuse or something more serious with the locking mechanism control module. Interesting that yours was just a loose connection, hopefully mine will be a similarly straightforward fix rather than needing a full module replacement.

The loose connection I mentioned was definitely the easier scenario. Given what you described with the fault code pointing to the fuse box and both key fobs not working, this sounds more complex than my case. The fact your car alarm still works but the keyless entry system is completely unresponsive suggests the issue might be in the central control module rather than just wiring. When my technician explained the system, they mentioned the fuse box contains multiple fuses specifically for the central locking and keyless entry functions. In my case, they first checked all fuses related to the door locks before discovering the loose connection. Since your diagnostic tool points to the fuse box area, have them thoroughly inspect not just the fuses but also the surrounding wiring and connections. In these models, water damage in this area can sometimes cause similar symptoms. The repair cost might be higher if they need to replace the control module. When they initially suspected this in my car, they quoted around 450 Euro for parts and labor. Luckily, it turned out to be just the wiring issue. Since both key fobs are not responding despite new batteries, and the fault code specifically points to the fuse box area, getting it professionally diagnosed is definitely the right move.

Thank you for following up and providing more details about your car's locking system. The fact that neither key fob works even with new batteries, while the alarm still functions, is making me lean toward checking the entire control module. Going to book it in at the workshop tomorrow and will ask them to start with a thorough inspection of the fuse box area since the fault code points there. Really hoping its just a fuse or wiring issue like yours was, rather than needing a full central locking module replacement. The 450 Euro estimate you mentioned for module replacement seems about right based on what I researched. Will update this thread once I get the diagnosis and repair completed, since it might help others with similar keyless entry problems. Thanks again for sharing your experience, its helpful to know what potential issues to discuss with the technicians.