SQ5 Alarm System Failure: Siren Issues & Fixes

Similar signal problem occurred on my 2015 S5, which shares many electrical components with the Q models. Have some experience working with automotive alarm systems, but always recommend professional diagnosis for security features. The wiring issue in my case was a faulty connection between the alarm controller and siren unit. Initially thought it was the entire vehicle security module, but turned out to be much simpler. The workshop found corroded plug contacts affecting the alarm system communication. Total repair cost was 95 Euro, covering diagnostic work and fixing the cable connection. Main work involved cleaning contacts and replacing a damaged wiring connector. No need for complete system replacement or alarm reset. For a more accurate assessment of your situation, could you share: Are there any other electrical issues present? Does the central locking still work normally? Can you hear any clicking sound from the siren location when arming/disarming? Have you noticed any water damage or signs of moisture near the alarm components? This information would help determine if you are dealing with a similar wiring issue or something more complex in the alarm system.

Thanks for the detailed response. My vehicle just had its service at 119223 KM and all other electrical systems are working fine. Central locking functions normally, but there is no clicking sound during alarm disarm attempts. The fault detection warning appeared right after a particularly heavy rain, which makes me suspect water might have affected the alarm controller connections. No visible moisture damage under the hood, but I have not checked the siren housing area yet. Based on your experience, should I first attempt checking the connector points before going for a full automotive alarm system diagnosis? The 95 Euro repair cost sounds much better than the 500 Euro+ quote I received for a complete alarm reset and component replacement.

Thanks for those additional details about your SQ5. Your symptoms match exactly what I experienced with my S5, especially the timing with the heavy rainfall. Water intrusion is a known weak point for these alarm system components. The complete lack of clicking sounds during disarm attempts strongly suggests a communication break between components, just like in my case. Since your central locking works fine, this further points to a wiring issue rather than a full vehicle security system failure. Before spending 500 Euro+ on a complete alarm reset, definitely check the connector points first. On my S5, the siren housing area connection was the culprit, despite showing no obvious external damage. The workshop found that water had seeped into the plug housing, causing corrosion on the terminals and disrupting the automotive alarm signals. A few things worth checking: Clean and inspect all visible alarm system connectors, Look for water residue around the siren mounting area, Test the ground connection at the siren mounting point If these basic checks reveal similar corrosion issues, you are likely looking at a straightforward wiring repair rather than a complete security system overhaul. The initial diagnosis should confirm whether your case matches my repair experience.

Your experience sounds very similar to mine and really helpful. After inspecting the siren housing area more carefully today, I found signs of water intrusion around the connector points. Some corrosion is visible on the terminals, which matches what you described. Given the matching symptoms and similar circumstances with the rain, I will go ahead and have the wiring issue checked first before considering a complete alarm reset. The automotive alarm diagnosis should be fairly straightforward now that I know what to point out to the technician. Will schedule an appointment with a shop that has experience with vehicle security systems to inspect the connections and clean the corroded terminals. Hoping to get away with a repair cost closer to your 95 Euro rather than the quoted 500 Euro for a full system replacement. Really appreciate the detailed breakdown of your experience with the alarm controller problems. Saved me from potentially overpaying for unnecessary repairs. Will update once I get the wiring issue sorted.