M3 Brake System Warning Lights: Multiple Failures Reported

I have some experience working on BMWs. Had a similar issue with my 2009 BMW 335i (also owned a 135i before). The symptoms you're describing sound exactly like what I faced, multiple warning lights and that odd brake pedal feel. Turned out it wasn't the brakes themselves but an undervoltage problem affecting the ABS module. Took it to my trusted mechanic who diagnosed it. The repair involved checking the battery, alternator, and electrical connections. Total bill came to around 240 Euro, but it fixed all those warning lights and restored normal brake pedal feel. Could you share more details about when these symptoms started? Does it happen when the engine is cold or after driving for a while? Also, have you noticed any other electrical issues like dim lights or slow starter? This info would help determine if you're dealing with the same problem.

Thanks for sharing your experience! Just had my service done last month at 83426 KM, and I've noticed these symptoms started about a week ago, mostly when the car's been running for about 15-20 minutes. Haven't spotted any electrical issues like dim lights or starter problems, though. The brake pedal feels kind of spongy and sometimes requires more pressure than usual. Been keeping an eye on the battery voltage with my OBD scanner and it seems normal, but I'll definitely look into the ABS module. Really appreciate the tip about checking the electrical system, that's not something I'd considered!

Hey again! Thanks for providing those extra details about your M3. You know, after reading about your specific symptoms and timing, I'm even more convinced it could be similar to what I dealt with on my 335i. Even though your battery voltage readings look normal, those ABS module issues can be really sneaky. In my case, the spongy pedal feel started pretty much the same way, after driving for a bit. The weird thing was that my voltage also seemed fine at first glance, but my mechanic found that the voltage supply to the ABS module was fluctuating under certain conditions. The multiple warning lights were basically the car's way of saying "hey, something's not right with the electronic brake management system." I'd really suggest getting it checked by a BMW specialist rather than a general mechanic. These systems are pretty complex and interconnected. My regular mechanic actually missed it the first time and just checked the brake pads. Wasted money there, to be honest. Quick question, have you noticed if the warning lights temporarily go away after restarting the car? That was another telltale sign in my case. Also, might be worth checking if there's any correlation with using other electrical accessories like the AC or radio. Let me know what you find out!

Thanks so much for the follow-up! Actually, yes, I've noticed the warning lights sometimes do clear after a restart, but they usually come back after driving for a bit. That's really interesting what you mentioned about the voltage fluctuation to the ABS module. Just tried running the AC full blast while driving today, and it seemed like the brake pedal got even spongier! You've convinced me to skip my regular mechanic and go straight to a BMW specialist. Don't want to waste money on unnecessary brake pad replacements if the real issue is with the ABS module. I'm going to book it in tomorrow and make sure to mention all these symptoms, especially the connection with the electrical system. Really appreciate you taking the time to share your experience, it's been super helpful in narrowing down what might be wrong. I'll let you know what the specialist finds!