An optional feature on many BMW's is the proprietary traction control system known as DSC, which stands for Dynamic Stability Control. When your DSC stops working or you are receiving an error light on your dashboard, there are a couple of components in the DSC system which could be causing the failure. These components include speed sensors, brake sensors, and adjustment sensors. If the wiring corrodes or one of these sensor malfunctions, the entire DSC system may not function properly.
Check the connection speed sensors located on each wheel hub. Locate them by following any wiring coming out of the wheel hub and following it until you've found the sensor. Check if the sensor is dirty or if its wiring has frayed or become disconnected somehow.
Check the brake components of your BMW by inspecting the rotors and brake pads that are on each corner of the car. If the pads are unevenly worn, your rotors are worn down (indicated by scratch-like marks on the surface of the rotor), or if the brakes are not functioning as well as they normally do, the DSC could be malfunctioning due to an issue with the braking system.
Check the adjustment sensors such as the steering angle sensor, lateral acceleration sensor, and pressure sensor by bringing the BMW to a licensed mechanic or BMW dealership. Using electronic diagnostic equipment, they can run tests on your DSC system to determine if any of the three aforementioned sensors are failing, and thus causing the issues with DSC.