BMW Z4 Multiple Warning Lights, Brake System Mystery

Hey! I have some experience working on BMWs. Actually, I had a similar issue with my 2021 BMW M4 last summer. Those warning lights combo usually rings alarm bells, but in my case, it turned out to be an undervoltage problem, not the brakes at all. My car started showing the same symptoms, multiple warning lights and weird brake pedal feel. Took it to my trusted workshop where they diagnosed a failing voltage regulator that was causing electrical issues throughout the system. The fix cost me about 240 Euro, but it solved all the warning lights and brake feedback problems completely. Before I share more specific details, what engine variant does your Z4 have, and did you notice any other electrical issues like dimming lights or slow power windows? These details would help determine if you're facing the same problem I had. By the way, if it helps, I also own a 320i and these BMWs can be quite sensitive to electrical issues. Let me know those details and I'll try to help further.

Thanks for sharing your experience! My Z4 has been pretty reliable until now (47011 KM on the clock, last serviced about a month ago). I haven't noticed any electrical issues like dimming lights or slow windows, everything else seems to work perfectly fine. The brake pedal feels a bit spongy though, which makes me lean more towards it being a mechanical rather than electrical issue. But you've got me thinking about checking the voltage now too, especially since these warning lights started appearing all at once. I'll definitely have them check both possibilities at the workshop. Really appreciate your detailed explanation about what happened with your M4!

Hey again! Thanks for those extra details about your Z4. You know, after hearing about the spongy brake pedal and no other electrical symptoms, I'm actually starting to think this might be different from what I experienced with my M4. Given that you're feeling sponginess in the pedal, there's a chance you might be dealing with air in the brake lines or possibly a master cylinder issue. When my M4 had the voltage problem, the pedal felt more stiff and unresponsive rather than spongy. I remember when I first bought my M4, the dealer mentioned that these newer BMWs have really sensitive brake monitoring systems. While my issue turned out to be electrical, that spongy feeling you're describing sounds more like what my dealt with on his M4, turned out he had a small leak in one of the brake lines that was letting air into the system. Since you mentioned your car was recently serviced, maybe they disturbed something in the brake system during maintenance? Either way, I'd definitely get it checked soon, these braking issues aren't something to mess around with. Keep me posted on what they find, I'm really curious to know if it's something completely different from what I experienced!

Thanks so much for the follow-up! You've actually made me feel a bit better about this whole situation. I'm thinking you might be right about the air in the brake lines, that would explain the spongy pedal feel perfectly. I've booked the car in for tomorrow morning and specifically asked them to check the brake lines and master cylinder, along with doing a voltage test just to be thorough. Really appreciate you taking the time to share your M4 experience and your 's brake line issue, it's given me a much clearer picture of what to expect. The timing with the recent service does seem suspicious now that you mention it. I guess some air could have gotten trapped in the system during maintenance. I'll keep you posted about what they find, might help someone else who runs into similar issues with their BMW in the future. Thanks again for all the helpful advice!