C0420
Pre-Collision System Malfunction
2014-2021 Mazda Mazda6 2.5L I4
High SeverityChassisGeneric (SAE)
Description
General fault in the pre-collision system that prepares or initiates emergency braking.
Symptoms
- Pre-collision system warning light
- Automatic emergency braking disabled
- Forward collision alert unavailable
- Driver assist systems degraded
Common Causes
- Radar or camera sensor fault
- Control module failure
- Brake system fault preventing intervention
- CAN communication error between modules
Diagnostic Steps
- Check for radar and camera codes first
- Verify brake system is fully operational
- Test CAN communication between PCS modules
- Check all sensor alignments
- Inspect wiring to PCS components
Repair Notes
Diagnose root sensor or communication fault. PCS depends on multiple subsystems.
Related Codes
Other Chassis Codes
- C0021LF Wheel Speed Sensor Range/Performance
- C0022RF Wheel Speed Sensor Range/Performance
- C0023LR Wheel Speed Sensor Range/Performance
- C0024RR Wheel Speed Sensor Range/Performance
- C0025LF Wheel Speed Sensor Circuit Intermittent
- C0026RF Wheel Speed Sensor Circuit Intermittent
- C0027LR Wheel Speed Sensor Circuit Intermittent
- C0028RR Wheel Speed Sensor Circuit Intermittent
- C0035Left Front Wheel Speed Sensor Circuit
- C0036Left Front Wheel Speed Signal Erratic
C0420 on Other Vehicles
Common Questions
What does code C0420 mean on a 2014-2021 Mazda Mazda6?
C0420 stands for "Pre-Collision System Malfunction". General fault in the pre-collision system that prepares or initiates emergency braking.
What are the symptoms of C0420 on a Mazda Mazda6?
Common symptoms of C0420 include: Pre-collision system warning light, Automatic emergency braking disabled, Forward collision alert unavailable, Driver assist systems degraded.
What causes C0420 on a 2014-2021 Mazda Mazda6?
Common causes of C0420 include: Radar or camera sensor fault, Control module failure, Brake system fault preventing intervention, CAN communication error between modules.