BMW M4 Battery Problems? Common Causes and Solutions

Hey there! I had a similar issue with my 2020 BMW M3 last winter (I have some experience working on cars, but mainly basic maintenance). Those symptoms sound exactly like what I dealt with, warning lights, weak starts, dimming lights. Turned out to be a faulty battery sensor, just as you suspect. Took it to my regular workshop, and they diagnosed it pretty quickly. The sensor wasn't reading the battery charge correctly, causing all those warning messages. They replaced the sensor, recalibrated the system, and I was good to go. Cost me around 315 Euro, including parts and labor. Haven't had any issues since then. Just to help better, what's your current battery age and have you noticed any other electrical issues? Also, did you scan for error codes? This could help confirm if we're dealing with the same problem. If you're having the exact same symptoms, I'd recommend getting it checked soon, these issues can sometimes lead to bigger problems if left unchecked. The M340i in our family had similar issues too, so it seems pretty common in recent BMW models.

Thanks for the detailed response! Yeah, my battery's been original since I got the car at 102702 KM. Glad to hear you got yours sorted out. I actually did get some error codes scanned at a 's workshop, showed battery sensor communication errors. Definitely sounds like the same issue you had. Just wondering though, did you notice if your radio or other electronics were acting weird before you got it fixed? My stereo's been out of nowhere resetting lately, and I'm guessing it might be related. Could that sensor really cause all these quirks? Going to book it in next week, but trying to gather as much info as possible before I head to the shop. Also, good to know about the cost. Was starting to worry it might be something more serious with the charging system. Haven't had any issues until now, and the car's been really solid otherwise. Really appreciate you sharing your experience!

Hey again! Yeah, I remember having those exact same issues with my M3, the radio resets were actually what got me really worried in the first place! It's funny you mention that because it was one of those little things I didn't connect to the battery sensor problem initially. But once it was fixed, all those electronic quirks disappeared. The sensor definitely can cause all sorts of weird electrical issues. In my case, the stereo would reset out of nowhere, especially during cold starts, and sometimes the central locking would act up too. The sensor basically tells the car's computer how much juice the battery has, so when it's faulty, all sorts of systems get confused. Just a heads up, when I got mine fixed, they told me it's pretty common in these models when they hit around 100,000 KM. The original sensor just tends to wear out. Since you're at similar mileage to when I had my issue, I'm even more convinced we're dealing with the same problem. One thing I'd recommend, when you take it in, ask them to check the alternator too, just to be safe. In my case, it was just the sensor, but it's good to rule everything out while they're at it. Trust me, once they sort this out, your car will be back to normal. Those electronics issues drove me nuts for a while! Let me know how it goes when you get it fixed, always good to compare notes on these things. These BMWs are fantastic cars, but they do have their quirks!

Thanks so much for all this info! You've honestly made me feel a lot better about the whole situation. It's such a relief to hear someone else had the exact same problems, especially those unusual radio resets that were driving me crazy! Can't believe I was stressing so much about this when it seems like such a common issue at this mileage. Really smart tip about getting them to check the alternator too, definitely going to mention that when I take it in. Better to be thorough while they're already working on it. Going to call the shop right now actually, while all this is fresh in my mind. Was a bit nervous about potential repair costs, but 315 Euro sounds way better than what I was imagining. Thanks again for taking the time to share your experience, really helped me understand what I'm dealing with. I'll try to remember to update you once it's all sorted!