BMW M2 ABS Malfunction: Speed Sensor or Bigger Problem?

Hey there! I had a similar issue with my 2018 M4 last year (I have some experience working on cars, but mostly basic maintenance stuff). The symptoms were almost identical, persistent ABS light, unusual traction control engagement, and those annoying error codes. Took it to my workshop thinking it was just a sensor, but turns out the ABS control unit itself was faulty. The whole diagnosis and repair set me back about 1000 Euro, not cheap, but it fixed the problem completely. The control unit needed to be replaced and recoded to work with the car's systems. Before jumping to conclusions though, could you share: Have you noticed any other warning lights? Does it happen more when turning or going straight? What error codes exactly did you get? This could help pinpoint if you're dealing with the same issue I had with my M4 (BMW has used similar ABS systems across the M series).

Thanks for the detailed response! Mine's at 199017 KM and just had its service last month. You're describing exactly what I'm experiencing, it's happening mostly while going straight, and the ABS light is the only warning I'm getting. Got error codes P0121 and C1233 when I scanned it. I was hoping it would just be a sensor since that's a cheaper fix, but what you're saying about the control unit makes sense given the symptoms. I'll definitely get it checked out properly. Did your mechanic try cleaning the sensors first before going for the full unit replacement? Just trying to explore all options before dropping that kind of money on repairs.

Hey again! Yeah, I totally get wanting to try the cheaper options first, I was in the same boat! When I had the issue with my M4, my mechanic actually did try cleaning the sensors and checking all the connections first. We even replaced one sensor just to be sure, but the problems persisted. The error codes you're getting are very similar to what I had. The P0121 was what initially made me think it was just a sensor issue too. But after the cleaning and sensor replacement didn't work, that's when we figured out it had to be the control unit itself. Here's something interesting though, before replacing the whole unit, my mechanic tried resetting the system multiple times, but the errors kept coming back within a few miles of driving. The jerky acceleration was actually getting worse over time, just like you're describing. Given that your car is showing the exact same symptoms as mine did, and you've got similar mileage (mine was around 185000 KM when it happened), I'd bet you're dealing with the same control unit issue. It's a known weak point in these models. If you want to save some money, maybe have them do a thorough diagnosis first, but honestly, be prepared for the control unit replacement. It's pricey, but it's better than dealing with unreliable ABS and traction control. How's the problem now, has it gotten any worse since your first post?

Thanks for sharing your experience with the M4! Yeah, unfortunately, things haven't improved since my first post. Actually, the jerky acceleration is getting more noticeable, especially during my last few drives. Really starting to feel unsafe with the unpredictable ABS behavior. After what you've shared about your similar experience, I think I'm going to bite the bullet and get it properly checked out this week. Makes sense to start with the sensors, but I won't be surprised if it ends up needing the control unit replacement. Rather spend the money now than risk any safety issues or more expensive repairs down the line. Really appreciate your detailed insight, it's helped me understand what I might be dealing with. I'll probably update the forum once I get it sorted out, might help someone else with the same issue in the future!