BMW Z3 Electrical Nightmares: Battery or Something Worse?

Hey there! I have some experience working on cars, and I actually dealt with something similar on my 2002 BMW Z4. Funny enough, my also had comparable issues with his 3 Series from the same era. After getting those unusual error messages and electrical gremlins, I took it to my regular workshop. Turned out the battery wasn't holding charge properly, even though it looked fine at first glance. The alternator was working, but the battery wasn't accepting the charge correctly. The fix cost me about 290 Euro, which included a new battery and some diagnostics. Since then, no more unusual errors or start-stop problems. Before I can give more specific advice, could you share: How old is your current battery? Are these issues happening more during cold starts? Have you noticed any dimming headlights? Does the problem get worse after short trips? Let me know these details and I might be able to help further!

Thanks for the detailed response! I've got the same symptoms with my Z3 (115006 KM on the clock). Just had it serviced last month but these issues started popping up recently. The headlights actually do dim a bit during idle, and yeah, it's definitely worse after quick trips to the store. My current battery is about 3 years old, so it could definitely be the culprit. Getting those unusual errors is driving me nuts, especially since they seem to come and go without any pattern. Might take it to the shop and have them check both the battery and charging system based on your experience. Hoping it's just the battery and not something more serious!

Hey again! Thanks for those extra details about your Z3. After reading about your symptoms, I'm even more convinced it's similar to what I dealt with. Those dimming headlights during idle and issues after short trips are exactly what I experienced with my Z4! Just wanted to add, after I got my battery replaced, I learned something interesting from my mechanic. Apparently, these BMWs from our era are quite sensitive to battery health. Even a battery that's only 3-4 years old (like yours) can start causing these weird electrical gremlins. Mine was about 3.5 years old when it started acting up. One thing I forgot to mention in my first reply, before I got it fixed, I also noticed the radio would sometimes reset itself, and the power windows would act a bit sluggish. Did you notice anything like that? These were actually early warning signs I initially ignored. The good news is that if it is just the battery, it's a relatively straightforward fix. Since you mentioned you just had it serviced, maybe ask them to do a full electrical system check while they're at it. Better safe than sorry, right? Let us know what you find out! P.S., Make sure they check the alternator too. Though in my case it was just the battery, it's worth checking both since the symptoms can be similar.

Thanks for the follow-up! Actually, now that you mention it, I have noticed my radio resetting occasionally. Thought I was going crazy! My power windows have been a bit wonky too, especially the passenger side one. It's like it's struggling to go up smoothly. I just called the workshop and booked it in for tomorrow morning. Asked them specifically to check both the battery and alternator like you suggested. You've given me hope that this might be a straightforward fix rather than some complex electrical issue. Will update once I get the diagnosis, but I'm feeling much better about this now. Thanks for sharing your experience, really helpful to know I'm not the only one who's dealt with these weird electrical gremlins in these older BMWs!