BMW M4 Electrical Nightmare: Multiple System Failures

Hey there! I have some experience working on BMWs. I actually faced something really similar with my 2018 BMW M3 a few months back. Those symptoms sound exactly like what I went through, sluggish starts, warning lights going crazy, and electrical gremlins all over. Turned out my battery was completely shot, causing voltage drops that messed with pretty much every system. Got it sorted at my regular workshop, they tested the charging system and confirmed the battery was the culprit. Total fix including labor was around 290 Euro. Before you head to the shop, could you share: How old is your current battery? Are these issues happening more when it's cold? Has the car been sitting unused for long periods? Might help pinpoint if we're dealing with the same issue. Also worth checking if your M4 is still running the original battery, they typically need replacement every 4-5 years.

Thanks for sharing your experience! I'm having almost identical issues with my M4 (128736 KM). You've pretty much described my situation perfectly. My battery is actually the original one from 2016, so it's definitely due for replacement based on what you're saying. The problems have gotten worse lately, especially on colder mornings. I actually had to get a jump start last week. Since you mentioned similar symptoms with your M3 and it turned out to be the battery, I'll probably go ahead and get mine tested. Really helpful to know the full diagnosis and repair cost from your experience, gives me a good idea of what to expect. Just need to find a good workshop that knows their way around BMW electrical systems. Don't want to throw parts at it without proper testing, but sounds like the battery is the likely culprit here.

Yeah after seeing your mileage and hearing about the jump start, I'm even more convinced it's the same issue I had with my M3. These modern BMWs are super sensitive to voltage fluctuations, and when the battery starts going bad, they throw all sorts of weird errors. The jump start thing is exactly what happened to me too. Started with occasional slow starts, then one morning, nothing. Had to call a for a jump. That's when I knew I couldn't put it off any longer. Quick tip from my experience, when you get the new battery, make sure the workshop does a proper registration/coding. My cousin skipped that step with his 3-series and had warning lights for weeks until he got it properly coded. These cars need to know when they get a new battery to adjust charging patterns. Also, definitely get them to test the alternator while they're at it. Mine was fine, but it's worth checking since they'll have everything apart anyway. The whole job took about an hour at my workshop. Trust me, once you get that new battery in, you'll notice the difference immediately. All those unusual errors and system warnings should clear up right away. Keep us posted on how it goes!

Thanks so much for the detailed advice! Really glad I posted here before taking it to the shop. The tip about battery registration is especially helpful, definitely wouldn't have known about that. Will make sure to mention it when I take it in. Also appreciate the heads up about checking the alternator while they're at it. Makes total sense to test everything while it's being worked on. I've already called a few workshops and found one that specializes in BMW electrical systems. They're familiar with the coding requirements you mentioned, so that's reassuring. Getting it booked in for tomorrow morning, can't risk any more jump starts at this point! Will definitely look for that immediate improvement you mentioned once the new battery is in. Really hoping this solves all those unusual system failures and warning lights. Thanks again for sharing your experience. Made me feel a lot better knowing it's likely just the battery and not something more serious!