BMW 4 Series Stalling: Ignition Switch or Something Else?

Hey! I have some experience working on cars and dealt with something very similar on my 2015 BMW 3 Series. When my car started acting up with those exact symptoms, I initially panicked thinking it was something major. Took it to my regular workshop and turns out it was just a blown fuse affecting the ignition system. They replaced the faulty fuse, and it set me back 52 Euro, definitely a relief considering what I was imagining! Before you jump to conclusions about the ignition switch, can you tell us if there are any warning lights on the dash? Also, does this happen more often when the engine is cold or warm? This info would help narrow down if you're facing the same issue I had. FYI, the 3 Series and 4 Series share a lot of components, so there's a good chance we could be looking at something similar here.

Thanks for sharing your experience! Mine's at 91687 KM and had its last service about 2 months ago. Actually, no warning lights show up when this happens, which is making it even more frustrating to diagnose. It seems to happen out of nowhere regardless of engine temperature, had it die on me both right after starting and during a longer drive. I'll definitely have someone check those fuses first since that's a much cheaper fix than replacing the whole ignition switch. Was your fuse located in the main fuse box under the hood, or was it somewhere else? Just trying to check this myself before heading to the shop.

Hey again! Yes, I definitely remember helping you with this issue. Just to add to what I mentioned about my BMW 3 Series experience, the fuse that caused my problems was actually in the interior fuse box, not under the hood. It's behind the glove compartment in our models. But honestly, given what you're describing now, especially with no warning lights and the completely unusual occurrences, I'm starting to think it might not be just a fuse in your case. After I fixed my fuse issue, I actually had something similar happen again about 6 months later, and it turned out to be a failing crankshaft position sensor. The symptoms were almost identical, unusual stalling, rough running, no warning lights. Cost me about 300 bucks to replace, but it solved the problem completely. Since you mentioned your car was recently serviced, maybe check if they replaced any sensors or if they noticed anything unusual? Sometimes these issues can start showing up even shortly after a service if a sensor is on its way out. My mechanic told me these sensors typically start acting up around 90,000 KM, which is right where your car's at. Let me know what you find out, really curious if it's the same issue I had!

Thanks a lot for the detailed follow-up! You might be onto something with that crankshaft position sensor theory. Now that you mention it, the symptoms do line up perfectly. The weird thing is that during my last service, they didn't mention anything about sensors needing replacement, but I guess these things can go bad pretty quickly. I actually just called my mechanic and mentioned what you said about the crankshaft position sensor, he agrees it's worth checking out, especially given the mileage. Got an appointment for next week to have it properly diagnosed. I'll still check those fuses first though, since it's an easy DIY job. At least now I know where to look, thanks for the tip about the interior fuse box location! I really appreciate you taking the time to share your experience. Will definitely update you once I figure out what's actually causing the problem. Let's hope it's just the sensor and not something more serious!