BMW M2 Brake System Failures: Sensor & Pump Warning Signs

I dealt with similar issues on my 2017 BMW M4. The symptoms you're describing sound exactly like what I experienced after a poor brake bleeding job. The ABS pump was making weird noises, and the brake pedal felt really spongy. Turns out air got trapped in the ABS module during the bleeding process. The mechanic had to use a proper diagnostic tool to activate the ABS pump cycles while bleeding. Without this specific procedure, you can't get all the air out of the system. It's actually a serious safety concern if not fixed properly. Had to take it to a specialty shop to get it sorted properly. They had to do a complete system bleed with the right diagnostic equipment. The whole brake hydraulic system needs to be bled in a specific sequence. After the proper service, the brake pedal feel returned to normal, warning lights disappeared, and that annoying pump noise was gone. Make sure whoever works on it knows BMW brake bleeding procedures and has the right diagnostic tools. This isn't a job for a general repair shop.

Thanks for sharing your experience! That's really helpful to know about the proper bleeding procedure. I'm already seeing some similarities with my situation. Just curious, do you remember roughly how much you ended up paying for the complete system bleed? Also, have you had any other brake-related issues pop up since getting it fixed? I want to make sure I'm prepared for what I might be looking at cost-wise and if I should expect any other problems down the line.

Hey again! Happy to give you an update on my M4's brake situation. After getting it properly fixed by a specialist, I paid around 90€ for the complete system bleed, which honestly wasn't too bad considering the headache it was causing. The mechanic found that the brake booster pressure sensor was indeed playing up, just like we thought, but once they got the air out properly and fixed the sensor, everything went back to normal. I can tell you that since getting it sorted about a year ago, I haven't had a single brake-related issue pop up. The pedal feel is perfect now, no more warning lights, and that annoying pump noise is completely gone. Really night and day difference from before. Just make sure whoever works on yours uses the proper diagnostic equipment for the bleeding procedure, that's what makes all the difference. It's worth paying a bit more to get it done right the first time. Regular shops might charge less, but if they don't know the specific BMW bleeding sequence, you'll just end up paying twice.

Just got back from taking my M2 to a specialist mechanic, what a difference! You were totally right about needing the proper diagnostic equipment. The whole brake system bleed cost me a bit more than yours at 120€, but it was worth every penny. They found some trapped air in the ABS module, just like you mentioned. Honestly, such a relief to have it sorted properly. The brake pedal feels solid again, those annoying warning lights are gone, and that weird pump noise has completely disappeared. The mechanic walked me through everything they did, showing me why the specific bleeding sequence matters. Much better experience than my last mechanic visit! Really glad I reached out here first, saved me from going through another frustrating repair attempt at a regular shop. Thanks again for pointing me in the right direction with this. Time to enjoy driving my M2 properly again!