BMW Z4 Audio System Failing, Subwoofer & Speaker Issues

Hey there! This sounds familiar. Had a similar issue with my 2019 BMW M240i, and I've got some experience working on cars (not an expert, but I've dealt with my fair share of repairs). The symptoms you're describing match exactly what I faced, intermittent subwoofer failure and crackling sounds. Took it to my regular workshop and they diagnosed a faulty bass speaker. The repair set me back about 280 Euro, but it fixed the problem completely. Haven't had any issues since then. Before I can give more specific advice, could you share: Have you checked if it happens with all audio sources (radio, bluetooth, etc.)? Does the problem get worse when you go over bumps? What trim level is your Z4? Different audio systems were offered. If it helps, BMW also used similar audio systems in the 2021 M240i. Let me know these details and I might be able to share more relevant info from my experience.

Thanks for your detailed response! I've got a 2021 Z4 with 187732 KM on the clock, and yes, the issue occurs with all audio sources. It actually gets worse when going over bumps, and I've got the premium Harman Kardon system installed. Just had it serviced last month, but the techs didn't spot any obvious issues with the audio system. I'll definitely look into the bass speaker, that's super helpful to know about your experience. Did you notice if there were any warning signs before your speaker completely failed?

Hey again! Thanks for confirming those details. Yeah, your symptoms are exactly like what I experienced with my M240i, and now I'm even more convinced it's the same issue I had since you mentioned it gets worse over bumps. Looking back, I did notice some warning signs before the complete failure. Started with occasional "dead spots" in bass-heavy songs, then progressed to that annoying crackling sound, especially when hitting bumps. With the Harman Kardon system (which I also have), these problems are usually related to either a faulty speaker or loose connections in the wiring harness. In my case, the workshop found that the subwoofer's voice coil was damaged, pretty common issue in these models actually. Since you've got similar mileage to what I had when mine failed (I was around 180000 km), it makes sense you're experiencing this now. Quick tip from my experience, before you take it in, try playing some bass-heavy music at different volumes. If the problem gets worse at higher volumes, it's almost definitely the speaker itself rather than an amp issue. That's what helped my mechanic diagnose it faster. Let me know how it goes, always happy to share more details about what I learned through my repair process!

Thanks so much for all this information, it's incredibly helpful! Just tried your suggestion with the bass-heavy music test, and you're absolutely right. The problem definitely gets worse at higher volumes, especially with deep bass tracks. The crackling is super noticeable now that I'm specifically testing for it. I'll schedule an appointment with my workshop and make sure to mention the possibility of a faulty voice coil in the subwoofer. It's actually a relief to know this is a somewhat common issue and not something more serious with the entire electrical system. Really appreciate you taking the time to share your experience, saved me a lot of troubleshooting headaches! Will update once I get it checked out. Thanks again for all your help!