BMW Z4 Emergency Call System Issues, Battery Fix Help?

Hey there! I have some experience working on BMWs, and I actually faced a similar issue with my 2023 BMW M3. Like you, my emergency call system started acting up. After taking it to my trusted workshop, they diagnosed it as a completely drained emergency call backup battery. These batteries typically last several years but eventually need replacement. The fix was straightforward, they replaced the backup battery unit, and everything went back to normal. Cost me around 110 Euro total. Based on your description, it sounds very similar to what I experienced. But to be sure, could you share: Have you noticed any other electrical issues? Is your main car battery relatively new or old? Does the emergency call button show any light at all? Let me know these details, and I might be able to provide more specific advice!

Thanks for the detailed response! My Z4 has only done 6947 KM since I got it serviced last month, and everything else has been working perfectly fine. The main battery is actually pretty new, got it replaced about 8 months ago, and the emergency call button does light up, just doesn't function properly. Your experience sounds exactly like what I'm dealing with. Really appreciate you sharing the cost info too, that helps me know what to expect. Think I'll go ahead and get it checked out at the shop since it seems like a straightforward fix. Better safe than sorry with safety features like this!

Hey again! That's great info about your Z4. Yeah, since you mentioned the main battery is new and the button still lights up, I'm even more convinced it's the same issue I had with my M3. After my experience, I learned these emergency call backup batteries are designed to last around 4-5 years, regardless of your mileage or how new your main battery is. It's a completely separate system. When mine started acting up, it was similar, everything else worked fine, just that emergency call function was being weird. Since your symptoms match what I experienced (light working but reduced functionality), I'd say you're on the right track getting it checked. The fix was super quick on my M3, took the mechanic less than an hour. Just make sure they use a genuine BMW battery unit, that's what I did, and haven't had any issues since. Let us know how it goes when you get it fixed! Always good to share experiences so others can learn too.

Thanks everyone for your help! Just wanted to update that I took my Z4 to the shop today, and you were absolutely right, it was the backup battery for the emergency call system. The mechanic confirmed it needed replacement after about 5 years of use, just like you said. The repair went smoothly, took about 45 minutes, and cost me pretty much what you mentioned. They used a genuine BMW battery unit, and now the emergency call system is working perfectly again. The timing is actually shorter than normal, and there aren't any more error codes popping up. Really appreciate everyone's input, especially the detailed explanation about how these backup batteries work independently from the main battery. Saved me a lot of worry! I'll definitely keep this in mind for future reference, and hopefully this thread helps other BMW owners facing similar issues. Thanks again for helping me sort this out! Nothing beats getting advice from people who've dealt with the same problem.