RS7 Alarm System Failure: Siren Communication Error

Had the same alarm system fault on my 2016 S7. The security breach turned out to be a damaged wiring harness connection to the alarm siren unit in the rear quarter panel. The fault detection system kept triggering false alarms. The repair required removing interior trim panels to access and replace the entire alarm controller module plus rewiring the connection to the siren. This was a significant repair that took several hours since multiple components needed testing to isolate the exact failure point. The alarm disarm function started working properly again after replacing both the controller and wiring. This is typically not a DIY job since it requires specialized diagnostic equipment to reset and reprogram the security system. Important to note this can also indicate water damage to the siren unit itself, so proper diagnosis is essential. Would strongly recommend having a certified shop handle the repair since incorrect alarm reset procedures can cause additional system conflicts. The issue is serious enough to address promptly as it affects core security functions, but not one that impacts drivability or engine performance.

Thanks for sharing your experience with the alarm system fault. Pretty much identical to what I faced with my RS7 last month. My fault detection scan also pointed to the siren module and wiring issues. I am curious about the repair costs in your case. Any chance you remember what you paid for the complete fix? Also, has your alarm system been working properly since the repair, or have you noticed any other security breach warnings pop up? The reason I ask is that despite getting my alarm controller replaced, I still occasionally get some odd behavior when trying to disarm the system, especially during cold starts.

Good news on the repair front, my alarm system has been working flawlessly since getting it fixed. The mechanic found a faulty cable connection to the siren unit, which was causing the vehicle security system to malfunction. Total cost came to 95 Euro for the wiring repair, which was much less than I initially feared given the complexity of the alarm system. The fix completely resolved the siren communication fault and I have not seen any security breach warnings since. The alarm disarm function now works consistently, even during cold weather starts. This suggests your continuing issues might point to a different underlying problem, possibly with the alarm reset circuit or another component of the security system. Based on your description of intermittent disarm problems, you might want to have the temperature sensors checked, as they can sometimes interfere with the alarm system in cold conditions. The wiring issue in my case was straightforward once properly diagnosed, but these systems can be tricky with multiple potential fault points.

Finally got my RS7 fixed last week. After reading about your experience, I took it to a different shop that specializes in automotive alarm systems. Turns out the previous repair only addressed part of the issue. The new mechanic found corroded wiring connections and a failing temperature sensor that was causing the cold start security breach problems. The vehicle security system needed a complete rewiring job plus a new sensor unit. Total repair came to 450 Euro but worth every cent. The alarm reset and disarm functions are now working perfectly, even on the coldest mornings. No more unusual security warnings or system malfunctions. The new shop did a thorough job testing all alarm system components before and after the repair. Really glad I got a second opinion instead of living with the intermittent issues. The detailed diagnostic approach made all the difference in solving the problem completely rather than just patching it.