BMW M4 Convertible Top Failure: Common Sensor Issue?

Hey there! I had a similar issue with my 2020 BMW M440i last year. The convertible top was giving me the exact same symptoms, getting stuck and flashing warnings. After bringing it to the garage, they found it wasn't the hall sensor but rather a damaged wiring harness where the cables flex when the top moves. Some connections had become loose over time. The fix required replacing part of the wiring harness and recalibrating the convertible top system. It wasn't a quick fix, my car was in the shop for about 3 days while they traced the exact location of the fault and waited for parts. This was definitely a job for a specialist with proper diagnostic equipment. While it wasn't the most serious mechanical issue, it's not something you want to ignore. If the top gets stuck in an open position when it starts raining, you'll have bigger problems. I'd suggest getting it checked soon at a shop that specializes in BMW convertibles. Just a heads up, make sure they do a full diagnostic before starting any repairs. My first mechanic jumped to conclusions and wanted to replace more expensive components unnecessarily.

Hey there, thanks so much for the detailed reply about your M440i! That wiring harness issue sounds exactly like what I might be dealing with. Really helpful to know it wasn't the hall sensor, could save me some troubleshooting time. Mind if I ask what the final bill came out to? And has everything been working smoothly since the repair? Just trying to get an idea of what I'm in for.

Hey again! Actually, in my case it did turn out to be the hall sensor after all! Just got my M440i back from the shop last week. The mechanic found a defective hall sensor in the convertible top mechanism, and they also discovered a loose cable connection that was contributing to the problem. Total cost came to 95 € for the fix, which wasn't nearly as bad as I was expecting. Since the repair, the top's been working perfectly, smooth operation every time with no more warning lights or getting stuck mid-way. What a relief! I know in my first reply I mentioned thinking it was a wiring harness issue, but I wanted to update you with what actually fixed my problem. These convertible tops can be tricky to diagnose sometimes, but a good mechanic with the right diagnostic tools can sort it out. Feel free to ask if you need any other info! Really hope you get yours sorted as easily as mine was.

Thanks for the update! Really interesting how it turned out to be the hall sensor after all. Just got back from the mechanic myself actually, what a journey that was! After reading about your experience, I took my M4 in yesterday. The mechanic found a blown fuse and a faulty motor regulator, totally different from what I expected. Cost me more than yours though, around 300 for parts and labor. But hey, at least it's fixed now! The top's working like a charm again, smooth as butter. Funny how these convertible problems can be so deceiving at first. Thank goodness it wasn't anything major like a complete system replacement. The mechanic I found was super honest, took the time to show me exactly what was wrong. Way better than my last experience! Thanks again for sharing your story, it really helped me push to get this sorted quickly instead of waiting around. Time to enjoy some open-top driving again!