BMW 7-Series Alarm System Dead, Battery Suspect?

Hey there! I had a similar issue with my 2013 BMW 5 series last winter (I also own a 3 series). I'd say I have some experience working with cars, mostly basic maintenance stuff. My alarm system completely died on me one day. Took it to my regular workshop, and they diagnosed it as a dead auxiliary battery, these batteries typically last 7-8 years before giving up. Getting it replaced sorted everything out, including those pesky error codes. Cost me around 330 Euro for the whole job, parts and labor included. Before I can give you more specific advice, could you share: How long have you had these symptoms? Any other electrical issues showing up? When was the last battery replacement? Let me know and I'll try to help further!

Thanks for the detailed response! My car's been serviced regularly (last one at 81,461 KM), and this issue just started about a week ago. Haven't replaced the auxiliary battery since I got the car, so it's definitely due. No other electrical issues so far, everything else works perfectly fine. Really helpful to know about your experience, sounds like I'm dealing with the exact same problem. Think I'll get it checked out by my regular mechanic and have them replace that auxiliary battery. Appreciate the cost estimate too, gives me a good idea of what to expect.

Hey again! Yeah, based on what you're describing, it's definitely sounding more and more like the auxiliary battery issue I had with my 5 series. Since you mentioned your car's been properly maintained but the auxiliary battery hasn't been replaced yet, that's almost certainly your culprit. My car had about 95,000 KM when the alarm system failed, and it was the original auxiliary battery too. One thing I didn't mention before, I actually ignored the first signs for a couple of weeks (alarm system being a bit inconsistent) before it completely stopped working. Don't make my mistake! The sooner you get it sorted, the less chance of it affecting other systems. Since you're taking it to your regular mechanic, just make sure they use an OEM battery or at least a high-quality equivalent. I initially tried saving some money with an aftermarket battery, but ended up replacing it again after six months because it wasn't performing well. Learned that lesson the hard way! Let me know how it goes after the repair. I'm curious if your repair cost will be similar to what I paid. These BMWs can be tricky sometimes, but they're worth the hassle!

Thanks so much for the additional insights! Really good to know about the OEM battery recommendation, definitely don't want to deal with replacing it twice. I'll make sure to ask my mechanic specifically about that. The mileage comparison is super helpful too. Sounds like our situations are almost identical, and it's reassuring to know this is a common issue that can be fixed without too much drama. I've already called my mechanic and booked it in for next week. I'll probably message you back after the repair to let you know how it went and what they charged. Really appreciate all your help and advice, exactly what I was hoping for when I posted here! These luxury cars can be a bit finicky sometimes, but like you said, totally worth it when everything's running smoothly.