Audi Q2 Alarm System Failure: Siren Fault Detected

Having dealt with a similar alarm disarm issue on my 2016 Audi Q3 2.0 TFSI, I understand your frustration. Based on my moderate experience with automotive electrical systems, these alarm problems often trace back to wiring issues. In my case, the alarm would out of nowhere trigger and the system showed similar communication faults. After taking it to the workshop, they found a damaged wire connection at the siren unit. The insulation had worn through, causing intermittent signal problems with the alarm controller. The fix involved repairing the connection and checking the entire alarm circuit. Total repair cost was 95 Euro and took about 2 hours to complete. The alarm reset worked perfectly after that and no issues since. Could you share: Has the alarm ever worked correctly since you owned the car? Are there any other electrical issues present? Does the problem occur more frequently in wet weather? Have you noticed any damaged wiring in the trunk area? This information would help determine if your issue matches what I experienced or if it might be something different.

Last service was done at 185000 KM with complete electrical system check. You describe the exact symptoms I noticed. Started about 2 months ago with unusual alarm triggers. After running fault detection, our garage first suspected the alarm controller but clearing the error codes did nothing. Good point about checking the trunk wiring, will take a look there since thats where they found a corroded connector last time during service. One thing to add: during wet weather the system works fine. Issues only appear during very hot days, which might point to a different root cause than in your case. Did your garage mention anything about temperature-related alarm system failures?

Thanks for the additional details about the temperature correlation. That actually points to a different security breach pattern than what I experienced with my Q3. While my issue was moisture-related wiring damage, your symptoms suggest possible heat-related expansion affecting connections. When the garage fixed my alarm system, they mentioned that extreme temperatures can cause different types of fault patterns: Cold/wet issues usually indicate exposed wiring or corroded connections, Heat-related problems often point to failing solder joints or damaged connector housings Since your problems occur during hot weather and the system works fine when wet, I would suspect either: 1. A failing solder joint in the alarm controller that expands and loses contact when hot 2. A plastic connector housing that warps under heat These issues typically cost 150-300 Euro to diagnose and repair, depending on which components need replacement. Would suggest having them specifically check the solder points and connector housings while running fault detection in a heated environment to replicate the issue. Did you notice if clearing the error codes temporarily fixed the signal problem until the next hot day?

Thanks for that detailed insight. Yes, clearing the codes does temporarily resolve the signal problem until temperatures rise again above 30 degrees. Looking at service records, they did replace some connector housings during the 185000 KM service, but obviously missed this particular issue. Your explanation about heat-related expansion makes perfect sense given the symptoms. Will ask the workshop to focus on checking those solder joints and connector housings in the alarm controller area. The fault detection process you described seems more targeted than what they initially suggested. The 150-300 Euro estimate helps set realistic expectations. Much better than potentially replacing the entire alarm system which another garage suggested. Just booked it in for next week and specifically requested they check those components while simulating high-temperature conditions. Appreciate the thorough technical explanation and repair guidance. Will update once the workshop completes their diagnosis and repair.