BMW 1 Series Alarm System Dead: Help with Error Code

Hey! I've got some experience working on BMWs, though I'm not an expert. Had a similar issue with my 2018 BMW 2 Series diesel last year. The symptoms were exactly the same, no alarm sounds, totally silent when locking/unlocking. Turned out to be a faulty connection in the alarm siren wiring. My mechanic found a corroded plug connection that was causing the communication failure. The fix wasn't too complicated, they replaced the wiring harness and connector for the siren. Cost me 95 Euro and it's been working perfectly since then. Before you head to the workshop though, could you share what error code you're getting? Also, did this start suddenly or was it gradual? This info would help figure out if you're dealing with the same issue I had.

Thanks for sharing your experience! My 1 Series has done 100456 KM and had its last service just 2 months ago. The problem started quite suddenly last week, just woke up one morning and the alarm system was completely dead. Getting error code 934521 on the diagnostic. Good to hear your issue was just a wiring problem, gives me hope it won't be anything too major. Planning to take it to my mechanic this week, but wanted to gather some insights first. Really hoping it's just a similar wiring issue like yours and not something more complicated with the alarm module itself.

Hey again! Yeah, after reading about your mileage and the error code, I'm even more convinced it's probably similar to what I experienced with my 2 Series. Mine had around 95000 KM when the issue popped up, so pretty close to yours. The sudden failure is actually a typical sign of a wiring/connection issue, that's exactly how mine went too. One day perfectly fine, next day completely dead. The error code you're getting (934521) is actually the same one I had, which typically points to a communication breakdown between the alarm siren and the main module. Since you mentioned your recent service, it's worth checking if maybe something got disturbed during that work. Sometimes these issues can pop up after routine maintenance if a connector wasn't fully secured. In my case, the corrosion had been building up for a while, but the connection finally gave out all at once. Keep us posted on what your mechanic finds! If it turns out to be the same wiring harness issue, the fix should be pretty straightforward and relatively inexpensive. The part itself isn't too pricey, and labor time is usually around an hour or so.

Thanks so much for the detailed response! That's really reassuring to hear that we had the same error code and similar circumstances. You've definitely put my mind at ease about this whole situation. I hadn't even thought about the recent service possibly being connected to the issue, that's a really good point. I've just called my mechanic and managed to get an appointment for tomorrow morning. I'll make sure to mention the wiring harness possibility and the connection to the recent service work. It's such a relief to know it might just be a straightforward fix like yours was. Really appreciate you taking the time to share all this information, it's super helpful going into the workshop with some idea of what might be wrong. I'll probably update this thread once I get it sorted, in case anyone else runs into the same problem in the future.