C0421high severityChassis
Pre-Collision Brake Actuator Circuit
on 2016 Subaru Outback 2.5L H4 · AWD
What this code means
Malfunction in the brake actuator used by the pre-collision system to automatically apply brakes.
Symptoms
- PCS warning light
- Automatic braking will not activate
- Pre-collision system disabled
Common causes
- Brake actuator solenoid failure
- ABS modulator fault affecting PCS
- Wiring to actuator damaged
- Actuator mechanically stuck
Diagnostic steps
- Test brake actuator solenoid resistance
- Command actuator with scan tool
- Check for ABS codes that disable PCS
- Inspect actuator wiring
- Test brake pressure response to PCS command
Repair notes
Replace brake actuator or repair ABS modulator. PCS brake actuation may use the ABS hydraulic unit.
Other Chassis codes on this vehicle
C0021
LF Wheel Speed Sensor Range/Performance
C0022
RF Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0025
LF Wheel Speed Sensor Circuit Intermittent
C0026
RF Wheel Speed Sensor Circuit Intermittent
C0027
LR Wheel Speed Sensor Circuit Intermittent
C0028
RR Wheel Speed Sensor Circuit Intermittent
C0035
Left Front Wheel Speed Sensor Circuit
C0036
Left Front Wheel Speed Signal Erratic