Q5 Security Alarm Failure Points to Anti-Theft System

Had a similar issue with my 2018 Audi Q3. The alarm system completely failed, including the optical locking signals. After multiple diagnostic runs, it turned out the main anti-theft control module was getting false readings from a faulty alarm sensor near the hood. The immobilizer was still working fine, but the car alarm would not arm properly and the indicators stopped flashing when locking. The problem was actually more serious than initially thought, as water had damaged the main control unit wiring. This created an intermittent power failure to the entire security system. The repair required replacing both the alarm sensor and rewiring part of the anti-theft system harness. A full system recoding was also necessary to get the optical locking signals working again. The job took about 4 hours at a specialized workshop since accessing the damaged wiring was quite complex. This type of alarm system failure often indicates deeper electrical issues that basic diagnostics might miss. Based on your description, your Q5 seems to have very similar symptoms to what my Q3 experienced. Would strongly recommend having it checked at a workshop with advanced diagnostic capabilities for security systems.

Thanks for sharing your experience. Those wiring issues with the security alarm can be really tricky. Just wondering how much the total repair ended up costing you? My anti-theft module is starting to show similar symptoms and I want to budget accordingly. Also, have you had any false alarms or other security system problems since getting it fixed? For my case, the local mechanic already quoted 450 Euro just for diagnostics, which seems quite steep compared to regular maintenance checks.

The repair bill came in much lower than expected at just 45 Euro for recoding the alarm system settings and optical locking indicators. No parts replacement was needed in my case, unlike the complex wiring issues I initially suspected. The alarm control has worked flawlessly since the fix. No false alarms or immobilizer problems at all. The anti-theft system now functions exactly as intended, with proper indicator flashing when locking and unlocking. That 450 Euro diagnostic quote does sound excessive. Since my alarm sensor and overall security system just needed a software reset rather than component replacement, the total cost stayed minimal. If your symptoms are similar, you might want to start with basic system diagnostics before agreeing to more extensive troubleshooting. Consider checking if your Q5 simply needs a control module recalibration first, as this could save substantial repair costs. A qualified technician should be able to determine this without charging premium diagnostic fees.

I finally got the car alarm issue resolved last week, and wanted to share how it turned out. After getting frustrated with the high diagnostic quotes, I found a specialized workshop that focused on security systems. Turns out the power failure was much simpler than expected. The alarm control module had a loose connection that was causing intermittent issues with the entire security alarm. The technician found it within 30 minutes using their advanced diagnostic equipment. The total repair only cost 180 Euro, which included a full system check and reconnecting the wiring. The anti-theft system now works perfectly, no more unusual failures or error codes. The workshop also updated the alarm system software as part of the service. Much better outcome than the 450 Euro diagnostic fee my regular mechanic wanted to charge. The car security features are all functioning normally now, including the optical signals when locking and unlocking. Really glad I got a second opinion from specialists who knew exactly what to look for.