Alfa Alarm System Failure: Common Solutions & Costs

Having some experience with Alfa models, I encountered a similar issue on my Alfa 159 2.2L from 2008. The anti-theft system was showing similar symptoms with immobilizer and alarm control problems. After diagnosis, it turned out the alarm control module needed recoding. The indicators were out of nowhere flashing due to a programming issue in the security system. The workshop found stored error codes related to the central locking system which were causing conflicts with the immobilizer. The fix involved reprogramming the alarm control unit to properly recognize the optical locking signals. Total repair cost was 45 Euro for the software update and system check. This resolved both the alarm functionality and cleared the stored ECU errors. To better assist with your specific case, could you share: Production year of your 156, Whether the central locking still works normally, If the immobilizer warning light stays on, When the problems first started appearing These details would help determine if your issue matches the common power failure pattern in the security module that affected several Alfa models from that generation.

Last service was at 103100km and my issue persists. After trying the suggested software update at the workshop, the anti-theft system is still non-responsive. The central locking now works intermittently, and the alarm control module shows additional error codes. The power failure symptoms have actually gotten worse, with the alarm going off out of nowhere even when the car is securely locked. Will need to investigate if the security module needs complete replacement rather than just reprogramming.

Thanks for the update about your ongoing alarm system issues. My 159 actually went through something similar, the initial software fix only worked temporarily before the security alarm started acting up again. The unusual alarm triggers and central locking problems point to a failing alarm control module. When mine deteriorated further, the immobilizer would occasionally engage without warning, which matches the common power failure pattern in these units. After trying the software update route like you did, I ended up having to replace the entire security module. The repair cost was 290 Euro for the part plus 120 Euro labor. While expensive, it completely resolved all alarm system malfunctions and error codes. A few checks worth doing before replacing the module: Test all door contact sensors, Check wiring connections to the trunk, Verify battery voltage at the alarm control unit If those check out fine, you are likely dealing with the same internal module failure that was common on these models. The new unit will need proper coding to match your car keys, but should fix both the unusual alarms and intermittent central locking issues.

My 156 is from 2004 and I appreciate all the detailed feedback. After checking the door sensors and wiring connections as suggested, the anti-theft system is still malfunctioning. The intermittent central locking and unusual alarm activation match the symptoms of a failing alarm control module perfectly. The battery voltage readings at the module are normal, which confirms the alarm sensor issues are internal component failures rather than power-related. Given that software updates did not resolve the security system problems, I will proceed with replacing the entire alarm control unit. The quoted repair costs of around 410 Euro total seem in line with what others paid for similar fixes. At least now I know what to expect and can be confident this should permanently resolve both the false alarms and central locking problems rather than continuing with temporary software solutions. Going to schedule the module replacement next week. Will update the thread once the new alarm control unit is installed and coded to share if it fully resolved these frustrating anti-theft system failures.