Audi Q4 Alarm System Failure Causing Security Issues

I had a similar problem with my 2021 Audi Q4 Sportback e-tron last month. As someone with moderate experience working on EVs, I can say these car alarm issues can be tricky to diagnose. The security alarm system in my case was showing similar symptoms, complete failure and error messages. After checking the car alarm sensors, it turned out the system was incorrectly coded for the optical locking confirmation through the indicators. The immobilizer was actually fine, despite initial concerns. The fix was straightforward once diagnosed, just needed a recoding of the alarm module. Total cost was 45 Euro for the diagnostic and programming work. Since then, no false alarms or security system errors. Before suggesting specific solutions for your case, could you share: The exact error message displayed? When did the issue first appear? Any recent software updates or maintenance work? Are the indicators working normally otherwise? Does the central locking still function properly? This would help determine if your issue matches what I experienced or if its something different in the alarm control system.

Thanks for sharing your experience. My car has 141632 KM and was last serviced in Q4 2023. The error message shows Alarm Control Unit Malfunction with a power failure warning. Indicators work fine and central locking is normal. The security alarm problems started right after the last software update. The car alarm out of nowhere activates at night which is quite annoying. No maintenance work besides regular service and the software update. Based on what you described, sounds like my issue could also be related to incorrect coding. Will have it checked at service next week.

Thanks for the additional details. Based on what you described, your symptoms do sound similar to what I experienced, but with some key differences. The unusual alarm activation at night combined with the power failure warning points more toward a potential battery issue in the alarm control unit rather than just a coding problem like I had. Since your issues started after the software update, there might be a conflict between the new software and the alarm system parameters. However, the false alarms at night are a classic symptom of a weakening control unit battery, which the immobilizer system often interprets as tampering. In my case, the recoding fixed everything, but given your symptoms, you might need: 1. A battery replacement in the alarm control unit (typically around 150 Euro) 2. A system recalibration after the battery replacement 3. Possibly a rollback of the recent software update When you take it to service, mention specifically that the anti-theft system started acting up after the software update and that youre getting false alarms at night. This will help them focus their diagnostic efforts. Would definitely recommend having them check the alarm control unit battery first before trying any software solutions.

Thanks for all the input. I just wanted to update that I took the car to service today. Turns out you were absolutely right about the alarm control unit battery being the culprit. They found the battery issue was triggered by the software update which drained it faster than normal. The total repair came to 165 Euro including a new battery for the alarm control unit and complete recalibration of the anti-theft system. They also adjusted some parameters in the immobilizer to prevent future conflicts with software updates. The car alarm is now working perfectly, no more unusual activations at night. They did recommend keeping an eye on the system after future software updates, just to catch any potential issues early. Really appreciate the guidance. Saved me time by knowing what to tell them to check first. Would have taken longer to diagnose without pointing them toward the battery issue specifically.