The Collision Mitigation Braking System (CMBS) warning on your 2020 Acura TLX indicates a fault in the automatic emergency braking system. CMBS is a key AcuraWatch safety feature designed to help prevent or reduce frontal collision severity.
CMBS Function
Collision Mitigation Braking uses radar and camera sensors to detect vehicles and pedestrians ahead. When collision is imminent and you haven't responded, CMBS provides warnings and can apply brakes automatically to avoid or reduce impact severity.
Multi-Stage Alerts
CMBS operates in stages: First, visual and audio warnings alert you to potential collision. If you don't respond, the system applies light braking pressure. If collision is unavoidable, CMBS applies strong braking to reduce impact speed.
Sensor System
The TLX typically uses a combination of front radar (millimeter-wave) and a forward-facing camera for CMBS operation. Issues with either sensor can trigger system warnings and disable automatic braking.
Common Warning Causes
Radar obstruction (in the grille area) or camera obstruction (behind windshield) commonly causes CMBS faults. Sensor damage from impacts, calibration issues after service, or hardware failures can disable the system.
Windshield and Grille Areas
Keep both sensor areas clean. The camera needs a clear windshield; the radar needs a clean grille area. Damage to either area—windshield chips or grille impact—can affect CMBS operation.
Related AcuraWatch Features
CMBS shares sensors with other AcuraWatch features like Lane Keeping Assist and Adaptive Cruise Control. Faults may affect multiple features when a shared sensor fails.