BMW M4 Brake Light Error: DIY Fix or Dealer Visit?

Hey there! I had a similar issue with my 2018 BMW M3 last summer. Initially got the same brake light warning, and like you, I thought it was just the brake light switch. Turned out to be more than that, my brake control module was faulty, which was affecting the entire brake light system. The mechanic discovered that moisture had gotten into the module, causing intermittent electrical issues. They had to replace both the module and the wiring harness connected to it. It was definitely a serious electrical issue that needed immediate attention, especially since it affects safety systems. I wouldn't recommend driving too long with this warning active. I'd suggest finding a certified BMW specialist rather than a general mechanic. The diagnostic equipment they use makes a huge difference in pinpointing these electrical gremlins. When they fixed mine, they also updated the software, which apparently helps prevent similar issues from recurring. Best to get it checked soon, brake system warnings aren't something to ignore, even if the car seems to drive normally.

Hey, thanks for sharing your experience! That's really helpful info. Sorry to hear you had such a complex issue with the module and wiring. I'm wondering, would you mind telling me roughly how much the whole repair set you back? And has everything been running smoothly since the fix? I'm trying to get a sense of what I might be in for with my situation.

Hey again! Actually, I've got some good news to share, my situation turned out way better than expected! After I posted about my experience, I took my M3 to a different mechanic who quickly spotted that it was just a bad brake light switch, way simpler than my initial module problem diagnosis. The best part? It didn't cost me anything because it turned out I hadn't properly engaged the brake pedal when starting the car a few times (totally my bad!). The mechanic just reset the system and showed me the correct way to do it. Talk about a relief! The car's been running perfectly since then, no more warning lights or any brake-related issues. Really glad I got it checked out, even though I was initially worried it might be something major like my previous experience. Sometimes the simplest explanation is the right one! Hope this helps put your mind at ease a bit. These modern BMWs can be pretty sensitive with their warning systems, but that's not always a bad thing.

Wow, that's a huge relief to hear about your experience! Just got back from the mechanic myself, and you wouldn't believe it, my issue was actually pretty minor too. Turned out to be a loose connection in the wiring that was causing the error message. The mechanic found it during the diagnostic check and fixed it right up. The whole thing only took about an hour and cost me €150 for the diagnostic and repair work. Way better than what I was imagining! The guy also showed me what to look out for in the future and explained that these electrical gremlins can sometimes pop up in newer BMWs. Really glad I didn't put this off any longer. The car's running perfectly now, no more warning lights. Thanks again for sharing your story, it definitely gave me the push I needed to get this sorted. Guess we both learned that these issues aren't always as scary as they first seem!