BMW Z4 Start-Stop Failure & Random Engine Shutdowns

Hey there! I have some experience with cars and had a similar issue with my 2014 BMW M3 (my previous ride before switching to a 3 Series). The symptoms you're describing sound exactly like what I dealt with. My start-stop system was acting up, and I got those annoying unusual shutoffs too. After a few days of dealing with this headache, I took it to my trusted mechanic. Turns out the battery was severely discharged and on its last legs. Had to get it replaced, which set me back about 290 Euro, but it fixed all the issues completely. Can you share some more details about your Z4? Like how many miles are on it, when was the last battery change, and are you seeing any other electrical issues? This info would help confirm if we're looking at the same problem. Quick tip: If you're experiencing this, try not to delay getting it checked. Those unusual shutoffs can be pretty dangerous while driving.

Thanks for sharing your experience! My Z4 has 33125 KM on the clock and just had its service last month. Haven't changed the battery since I got it, so that could definitely be the culprit. Really appreciate the heads up about the battery, makes total sense given the symptoms. Will get it checked out ASAP since those unusual shutoffs are making me nervous. Better safe than sorry with these things!

Hey again! Thanks for those details about your Z4. Yeah, that mileage isn't super high, but what really caught my attention is that you haven't changed the battery since you got the car. That's exactly what happened with my M3, the original battery was still in there when all these issues started popping up. Just to share a bit more from my experience, after I got the battery replaced, I learned these start-stop systems are pretty demanding on the battery. My mechanic explained that constant stopping and starting puts a lot of strain on it, way more than regular driving. Even if the battery seems fine for normal use, it might not have enough juice for the start-stop feature. Since you mentioned you just had service last month, did they do a battery health check? Sometimes these issues can creep up pretty quickly. After my battery saga, I now make sure to get the battery tested during every service. Quick word of advice based on what happened with my car, if you're planning to get it checked, try to do it sooner rather than later. Those unusual shutoffs nearly got me into trouble once when I was merging into traffic. Let us know what you find out!

Thanks so much for the detailed follow-up! No, they didn't do a battery check during the service, wish I'd known to ask for one specifically. You're absolutely right about those unusual shutoffs being risky. Just yesterday, it happened while I was approaching a roundabout, and it really shook me up. Called my mechanic right after reading your message, and I'm taking it in tomorrow morning. Really grateful for your insights about the start-stop system being tough on batteries, wouldn't have made that connection myself. The fact that your situation was so similar with your M3 makes me pretty confident we're looking at the same issue. Will definitely get the battery tested first thing. I'll make sure to get a high-quality replacement if that turns out to be the problem. Thanks again for taking the time to share your experience, it's been super helpful!