BMW M4 Key Battery Issues? Quick Fix vs Major Problem

Hey there! I had a similar issue with my 2017 BMW M3 last year (I have some experience working on cars, mostly basic maintenance). The symptoms were exactly like yours, keyless entry stopped working and got that annoying warning on the dash. Took it to my trusted workshop since I wasn't completely sure about handling the key myself. Turned out it was just a dead battery in the key fob. The mechanic replaced it in about 10 minutes, cost me 37 Euro including labor. Quick tip: If you need to get in the car meanwhile, there's usually a backup way to use the physical key hidden in the fob. What's your exact error message? Also, how long have you been getting the warning? This could help determine if it's really just the battery or something else. Let me know and I can share more details based on my experience. By the way, make sure to mention your exact model year and if you've noticed any other electrical issues. Sometimes these things can be connected.

Thanks for sharing your experience! I've got a 2019 M4 with 30593 KM on the clock and just recently started getting this issue. The error message is exactly like yours, key battery warning on the dash. Haven't noticed any other electrical problems so far, and the car was running perfectly fine during my latest service. I wasn't too keen on messing with the key fob myself either, so your workshop solution sounds like the way to go. Good to know it was just a simple battery replacement in your case. Did your mechanic use an original BMW key battery? I've heard mixed things about using generic ones. Also, thanks for the tip about the physical key, definitely going to keep that in mind until I get this sorted!

Hey again! Yeah, you're definitely describing the same issue I had with my M3. When I took it in, my mechanic actually showed me the battery he was using, it was a genuine BMW CR2450 battery. He mentioned that while generic ones might work, he prefers using OEM parts for the key fob since he's seen some cheaper batteries drain faster. Honestly, with those symptoms and your mileage, I'd bet good money it's just the battery. Mine started acting up around 35000 KM, so pretty similar to yours. The whole thing was super straightforward, pop open the key fob, swap the battery, and boom, everything working again like new. Just so you know, after I got it fixed, I haven't had any issues with the keyless entry for over a year now. Though I did start keeping a spare key battery in my glovebox just in case, might be worth doing the same once you get yours sorted. Quick extra tip from my experience, I noticed that even before the warning came up, the key's range had gotten a bit shorter. Did you notice anything like that? It's usually one of the first signs that the battery's getting weak.

Thanks so much for all the detailed info! That's really helpful, especially about the genuine BMW CR2450 battery. I actually did notice the range getting shorter over the last few weeks but didn't connect the dots, now it makes total sense! I'll definitely get it checked out at the workshop this week. Feeling much more confident now knowing it's likely just a battery issue and not something more serious. And that's a brilliant idea about keeping a spare battery in the glovebox, will definitely do that once this is sorted. Really appreciate you taking the time to share your experience. It's exactly what I needed to know, especially coming from someone with a similar BMW. Think I'll skip the generic batteries and stick with the OEM ones, rather spend a bit more now than have to deal with this again sooner than necessary! Thanks again for all the tips. I'll get on this ASAP and hopefully be back to normal keyless entry in no time!