Audi A3 Door Lock System Complete Failure & Fix Tips

I had a very similar issue with my 2019 Audi A4 last winter. The central locking system completely failed, and the key fob stopped communicating with the car. As someone with some general car maintenance experience, I first tried the basic troubleshooting steps like you did with checking the fob battery. After taking it to the workshop, they diagnosed the problem as a faulty connection in the wiring harness that links to the locking mechanism control unit. The cable had developed a poor contact due to regular door movement over time. They had to partially disassemble the driver's door panel to access and repair the connection. The total repair cost was 95 Euro, which covered both diagnosis and fixing the defective cable connection. Since then, the keyless entry system has worked flawlessly. Before suggesting more specific solutions, could you provide: The exact engine variant of your A3, Whether this happened suddenly or developed gradually, If all doors are affected or just specific ones, Whether you notice any correlation with weather conditions, If any other electrical systems are showing issues This information would help determine if your issue matches what I experienced or might be something different in the central locking system.

Latest service was at 85000km. The problem appears to be different from what you experienced. While examining the wiring as you suggested, I discovered that water had entered near the door handle, causing corrosion in the locking mechanism connections. This explains why the remote locking failed first, followed by the complete failure of the central locking system. The security system warning light started blinking after the initial failure, suggesting the entire keyless entry module might be compromised due to moisture damage. Unlike your wiring harness issue, this seems more extensive and potentially costlier to repair. Did your repair involve checking the door seals? Since my A3 shows signs of water ingress, Im wondering if this could be a common weak point in these models?

Thanks for the additional details about the water damage. That definitely changes the diagnosis from my initial thoughts about the wiring harness. After my repair, I actually had the technicians check all door seals since water ingress can be a silent killer for car locks and electrical systems. In my A4, they found that the rubber seals around the door handle had started deteriorating, creating tiny gaps where water could seep in during heavy rain. The central locking issue you described sounds more severe than my original wiring problem. When water damages the locking mechanism and keyless entry components, corrosion can spread through the electrical connections. The blinking security light typically indicates the system detecting faults in multiple components. The repair might involve: Replacing the affected door locking mechanism, Installing new weather seals around the handles, Checking and possibly replacing the keyless entry module, Treating any corroded electrical connections My suggestion would be to get this addressed quickly since continued water exposure could lead to more extensive damage to the car locks and electrical systems. The repair cost will likely be higher than my 95 Euro wiring fix, possibly in the 300-500 Euro range depending on component replacement needs. Would you mind sharing if youve noticed any other electrical gremlins? Water damage rarely stays isolated to just the remote locking system.

Thank you for explaining about the water damage and car lock issues. The security system warning light blinking does point to more extensive problems than just the wiring harness issue you experienced. Looking at my A3 more closely now, I can see clear signs of water damage around the rubber seals near the door handle. Ive started noticing other small electrical issues that probably relate to the moisture problem. The passenger window sometimes acts sluggish, and occasionally the interior lights flicker when operating the doors. These symptoms emerged gradually over the past month, right before the central locking completely failed. Given how the water ingress has affected multiple systems beyond just the remote locking feature, I agree this will likely require more extensive repairs than just fixing a wiring connection. Based on your cost estimate of 300-500 Euro, I will budget accordingly and get it checked at the workshop this week before the damage spreads further. The corrosion around the electrical connections definitely explains why both the keyless entry and manual central locking operations stopped working. I appreciate your insight about the door seals, will make sure they check and replace all of them to prevent future water damage to the car locks and security system.