BMW 8 Series SOS System Failure: Battery or Something More?

Had the same problem with my BMW M4 (2015) last winter. The emergency call system started throwing error messages, and the backup battery was completely drained. Took it to my regular mechanic who diagnosed it right away, the emergency call system has its own separate battery unit, which typically lasts 3-4 years. Got it fixed at the shop last month. They had to replace the entire emergency call control unit since the battery isn't sold separately. The repair wasn't particularly complex, but it's definitely something you want a qualified technician to handle because of the system's safety implications. Not a major mechanical issue, but it's important to fix it since it's a critical safety feature. Make sure whoever works on it knows BMW systems well, the emergency call module needs proper coding after replacement. My advice: get it checked soon. These systems are designed to work when you need them most, so better not take chances.

Thanks for sharing your experience! The same thing happened to me back then and yeah, you're totally right about the battery unit. I'm curious, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been working smoothly since the fix, or have you noticed any other quirks with the system? Just want to make sure I'm prepared for what might come up with mine.

Hey there! Yes, absolutely, I got my M4's emergency call system fixed and it's been working perfectly ever since. The total cost was 110 € for fixing the completely drained emergency battery. Much cheaper than I initially feared, to be honest! Since the repair, the system's been running like clockwork, no error messages, no quirks, nothing to worry about. It's been about three months now, and it's such a relief not having those warning messages pop up anymore. The mechanic really knew what they were doing, and it shows in how smoothly everything's working now. I was actually a bit concerned at first that the problem might come back, but it hasn't. The tech explained that once they properly fix and code the new battery unit, it should last another 3-4 years at least. Just make sure you get a qualified BMW technician to handle it, it's worth paying for someone who knows these systems inside out. If you're worried about potential future issues, honestly, I wouldn't be. Once it's properly fixed, these systems are pretty reliable. Just keep an eye on it after the 3-year mark, and you should be good to go!

Thanks so much for all the details! I actually just got mine fixed yesterday. Had a similar experience, took it to a certified BMW tech who diagnosed it right away. The whole repair ended up costing me about 120 €, which wasn't too bad considering how worried I was initially. Funny story, while I was at the shop, they found out my backup battery was completely dead, even worse than they expected. The mechanic showed me the old unit, and wow, it was in rough shape! But they got everything sorted pretty quickly. The whole thing took about two hours, including all the coding work. What a relief to finally have this sorted. No more annoying error messages popping up on my dashboard! The tech also gave me some tips about maintaining the system, which was super helpful. They said I should be good for another few years now. Really appreciate everyone's help on this. It's great knowing others have dealt with the same issue and got it resolved without any major headaches. Time to enjoy driving without those pesky warning lights!