BMW ABS Warning: Lateral Acceleration Sensor Problems

Hey there! I had a similar issue with my 2002 BMW 3 series (also dealt with a BMW 5 series before). I've got some experience working on cars, but I'm not a pro mechanic. The same thing happened, ABS light suddenly popped up and the whole system went dead. After taking it to my trusted workshop, they diagnosed a faulty control unit. It wasn't just the sensor, the entire ABS control module had gone bad. Ended up costing me about 1000 Euro to replace it, but it fixed the problem completely. Could you share what error code you're getting specifically? Also, have you noticed any other warning lights or unusual behavior when braking? This would help narrow down if you're facing the same issue I had.

Thanks for sharing your experience! My car only has 38705 KM and was just serviced last month, so I'm a bit surprised by this issue. I'm getting error code 5E21B which points to the lateral acceleration sensor. No other warning lights are showing up, and the brakes feel normal except for the ABS not engaging when I need it. I was hoping it might just be a sensor issue rather than the whole control module, as that sounds pretty expensive to replace. Did your mechanic try cleaning or recalibrating the sensor before deciding to replace the entire unit?

Hey again! Thanks for providing those extra details about your BMW. You know, after reading your response, I'm actually thinking your case might be different from what I experienced. With such low mileage and recent service, you're right, it does seem unusual for the entire control module to fail. In my case, I actually had multiple error codes, not just the one you're getting. And yeah, looking back, I probably should've mentioned that my mechanic did try cleaning and recalibrating the sensor first (cost me about 100 Euro), but it didn't solve the issue. That's why we ended up replacing the whole unit. Since you're only getting that specific sensor error code (5E21B) and everything else seems to work fine, there's a good chance you're just dealing with a faulty sensor. My suggestion would be to have someone check the sensor connections first, sometimes it's just corrosion or a loose wire. Could save you a bunch of money compared to what I had to pay for the full module replacement. Have you noticed if the problem gets worse when driving on uneven surfaces? That's something I noticed with mine before the full replacement, but if you're not experiencing that, it might further confirm it's just the sensor.

Thanks for the detailed follow-up! That's really helpful info about checking the connections first. You've actually made me feel a bit more optimistic about this whole situation. No, I haven't noticed any difference on uneven surfaces, which does seem to support your theory about it being just the sensor. I've actually just booked an appointment with a mechanic for tomorrow morning. I'll definitely have them check the connections and clean everything before jumping straight to replacement parts. Really hoping it's just a connection issue or something simple like that! Thanks again for sharing your experience, it's given me a much better idea of what to discuss with the mechanic. Will update the forum once I know what's actually wrong with it!