BMW 4 Airbag Light & Soft Top Issues, Rollover Sensor?

Hey there! I've got some experience with BMWs and had a similar issue with my 2021 BMW 3 Series diesel (also have a 5 Series in the family). The airbag warning light came on, and I had issues with various electrical systems. Turned out the control unit was faulty, it was sending wrong signals to multiple systems. After struggling with it for a week, I took it to my workshop. They diagnosed it and had to replace the control unit completely. Set me back about 1000 Euro, but it fixed both the airbag warnings and other electrical gremlins. Before I can give you more specific advice, could you share: Which engine variant you have? Any other warning lights showing up? When did these issues start? Just want to make sure we're dealing with the same problem here before you spend money on repairs.

Thanks for sharing your experience! My issue started about 2 weeks ago, and I'm at 144711 KM. Just had my service last month, and everything was fine then. No other warning lights showing up at the moment, just the airbag one. I've got the 2.0L diesel engine. The timing of both issues (soft top and airbag warning) appearing together makes me think they're connected somehow. Really hoping it's just a sensor issue and not the entire control unit like in your case. The cost you mentioned has me a bit worried though! Did your mechanic try resetting the system first before replacing the unit?

Hey again! Yeah, I totally understand your concern about the costs. You know what, given that your issue started suddenly after being fine during service, there might still be hope for a simpler fix. In my case, the mechanic did try resetting the system first, they always start with the easiest (and cheapest) solutions. They connected their diagnostic tool and attempted a reset, but the warning kept coming back after about 20 minutes of driving. That's when they figured out it wasn't just a temporary glitch. With your mileage being similar to what mine was when I had the problem (I was at around 140K), it could indeed be the same issue. But here's a bit of good news, since you mentioned no other warning lights, it might actually be less severe than what I dealt with. In my case, I had unusual electrical glitches popping up all over. Quick question, have you noticed any issues with the car's stability control or other electronic systems? In my case, before the full failure, I had occasional ESP warnings that would come and go. This might help narrow down if we're dealing with the same problem. Just trying to save you from going through the whole expensive ordeal I went through if it's not necessary!

Thanks for all this detailed info! Really appreciate you taking the time to explain everything. No, I haven't noticed any ESP warnings or other electrical issues, which definitely makes me feel a bit more hopeful after hearing your experience. That's a good point about it possibly being less severe since I'm not seeing multiple problems like you did. I've just booked an appointment with my mechanic for next week. I'll definitely ask them to try the reset first before jumping into any expensive replacements. The fact that everything was fine during my recent service and this started suddenly does make me think it could be something simpler. I'll keep your experience in mind when talking to them, at least now I know what potential issues to discuss and what questions to ask. Thanks again for all your help! I'll update the thread once I find out what's actually causing the problem.