BMW Z4 Won't Start: Failing Starter or Battery Mystery?

Hey there! I had some experience (low experience) with something really similar on my 2020 BMW M2. Funny enough, it turned out mine was related to a previous repair where the workshop messed up the battery connections after doing some engine work. They fixed it free of charge since it was their mistake. The symptoms were exactly like yours, weak cranking, flickering lights, and error codes popping up. What's the mileage on your Z4? Also, have you had any recent work done on the car? This could help pinpoint if it's a similar situation to what I faced. Hit me up with those details and I can share more about what the workshop did to sort it out.

Thanks for sharing your experience! My Z4 has 25747 KM on the clock, and just had its last service a couple weeks ago. No other work has been done recently. Your situation sounds really similar to what I'm experiencing right now. Did your mechanic mention anything about battery voltage readings or alternator performance when they fixed yours? I'm thinking of taking it back to the same workshop that did my service, since they might have accidentally disturbed something during the maintenance work.

Hey again! Yeah, reading your details, this sounds even more similar to what happened with my M2. When I took it back, they actually found that during the service they hadn't properly tightened the battery terminal connections, it was creating intermittent contact which explained all those symptoms we both experienced. The mechanic did check the voltage readings, my battery was actually fine, showing around 12.6V when they finally got it properly connected. The alternator was working perfectly too, producing about 14V when running. It was literally just those loose connections causing all the drama! Since you've just had a service, I'd definitely take it back to the same workshop. Sounds like they might have done exactly what happened to mine, just not secured everything properly after the service. These symptoms are classic signs of poor electrical connections rather than a failing component. Best part? Since it was their mistake with my M2, they sorted it at no cost. Given your timing is so close to the service, I reckon you might be in the same boat. Just make sure to mention the timing of when these issues started relative to the service. They should be pretty understanding about checking it out.

Thanks so much for all that detailed info! You've actually made me feel a lot better about this situation. I was worried I'd be looking at a major repair bill, but hearing that yours was just a connection issue that got sorted for free is really reassuring. I've already called the workshop and they've agreed to check it out tomorrow morning. They seemed pretty interested when I mentioned it started right after the service, so fingers crossed it's just loose connections like yours was! Really appreciate you taking the time to share your experience, it's helped me understand what might be going on and saved me a lot of worry. I'll update the thread once I know what they find, might help someone else with similar issues down the line!