Pre-Collision Brake Actuator Circuit
2016-2018 Lincoln MKX 3.7L V6
Description
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.
Related Codes
Other Chassis Codes
- C0021LF Wheel Speed Sensor Range/Performance
- C0021LF Wheel Speed Sensor Range/Performance
- C0022RF Wheel Speed Sensor Range/Performance
- C0022RF Wheel Speed Sensor Range/Performance
- C0023LR Wheel Speed Sensor Range/Performance
- C0023LR Wheel Speed Sensor Range/Performance
- C0024RR Wheel Speed Sensor Range/Performance
- C0024RR Wheel Speed Sensor Range/Performance
- C0025LF Wheel Speed Sensor Circuit Intermittent
- C0025LF Wheel Speed Sensor Circuit Intermittent
C0421 on Other Vehicles
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Lincoln Aviator Grand Touring
2020-2024 3.0L Twin Turbo V6 PHEV
Lincoln Aviator Grand Touring
2020-2024 3.0L Twin-Turbo V6 Hybrid
Lincoln Aviator Grand Touring
2020-2024 3.0L V6 Twin Turbo Hybrid
Lincoln Continental
2017-2020 2.7L EcoBoost V6
Lincoln Continental
2017-2020 2.7L Twin-Turbo V6
Lincoln Continental
2017-2020 2.7L V6 Twin Turbo
Common Questions
What does code C0421 mean on a 2016-2018 Lincoln MKX?
C0421 stands for "Pre-Collision Brake Actuator Circuit". Malfunction in the brake actuator used by the pre-collision system to automatically apply brakes.
What are the symptoms of C0421 on a Lincoln MKX?
Common symptoms of C0421 include: PCS warning light, Automatic braking will not activate, Pre-collision system disabled.
What causes C0421 on a 2016-2018 Lincoln MKX?
Common causes of C0421 include: Brake actuator solenoid failure, ABS modulator fault affecting PCS, Wiring to actuator damaged, Actuator mechanically stuck.