C0420high severityChassis
Pre-Collision System Malfunction
on 2015 Audi A6 3.0L Supercharged V6 · AWD
What this code means
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.
Other Chassis codes on this vehicle
C0021
LF Wheel Speed Sensor Range/Performance
C0021
LF Wheel Speed Sensor Range/Performance
C0022
RF Wheel Speed Sensor Range/Performance
C0022
RF Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0025
LF Wheel Speed Sensor Circuit Intermittent
C0025
LF Wheel Speed Sensor Circuit Intermittent