Mercedes-Benz Warning Message
“Brake Assist Malfunction”
The BAS (Brake Assist System) or ESP-linked emergency braking assist has failed. The vehicle will still brake, but emergency stopping distance is increased because the system no longer amplifies pedal force during panic stops.
high severity
Common Causes
- BAS control module fault (W211/W204 notorious)
- Brake pressure sensor failure
- ESP module communication error
- Brake light switch failure
- Steering angle sensor calibration drift
Immediate Action
Drive cautiously with increased following distance. The vehicle will stop, but emergency braking performance is degraded. Schedule service within 48 hours.
Typical Repair Cost
$500–$2,000