BMW i4 Warning Light Storm: Brake System Mystery

I experienced similar warning lights on my 2017 BMW i3. The multiple warning lights were actually triggered by an undervoltage condition in the 12V battery system, not a direct brake issue. Last month, my car started showing the same symptoms, mushy brake pedal feel and cascading warning lights (brake, ABS, ESP). At the garage, diagnostics revealed the 12V battery was failing to maintain proper voltage, which affects multiple vehicle systems including brake controls. The repair involved replacing the 12V battery and recalibrating the brake system. While it seemed alarming with all those warning lights, it wasn't a serious mechanical issue. The electronic brake systems are designed to enter a safe mode when voltage issues occur. I'd suggest getting the 12V battery and charging system checked first before diving into brake components. These symptoms are pretty common in EVs when the auxiliary battery starts failing.

Thanks for sharing your experience, this sounds exactly like what I'm dealing with! My brake pedal has that same mushy feel you described. Really glad to hear it wasn't a major mechanical problem in your case. Quick question, do you remember roughly how much you paid for the battery replacement and recalibration? Also, has everything been working smoothly since the repair? Just want to make sure I budget properly and know what to expect.

Hey there! Happy to give you an update. Since I got the undervoltage issue fixed for 240€, my i3 has been running like a dream. The mushy brake feeling completely disappeared after they sorted out the 12V battery situation and recalibrated everything. It's been about 3 months now, and I haven't seen a single warning light since. The brake pedal feels nice and firm again, exactly how it should be. Honestly, it was such a relief that it wasn't anything major with the actual brake system. I totally get why all those warning lights freaked you out, they did the same to me! But trust me, once they fix the voltage issue, you'll be good to go. These EVs can be a bit dramatic with their warning lights when the 12V system isn't happy. The repair cost was totally worth it for the peace of mind. Just make sure they do both the battery replacement and the recalibration, both steps are important to get everything working properly again.

Thanks so much for the detailed follow-up! I bit the bullet and took my i4 to a mechanic yesterday. You were spot on, it was the 12V battery causing all the drama. Total bill came to 275€ for the replacement and recalibration, a bit more than yours but still way better than what I feared. The funny part was watching the mechanic's face when all those warning lights disappeared like magic after the new battery went in. Took it for a test drive this morning and the brake pedal feels perfect now, no more mushiness. Really appreciate you sharing your experience. Saved me from stressing about potentially major brake repairs. These fancy EVs sure know how to give us a scare with their warning light shows! But hey, lesson learned about the importance of that little 12V battery. Thanks again for helping me sort this out. Time to enjoy my warning-light-free drives!