C0401moderate severityChassis
ACC Distance Sensor Circuit
on 2010 Audi R8 4.2L V8 · AWD
What this code means
General malfunction in the adaptive cruise control distance sensing radar or lidar unit.
Symptoms
- ACC system disabled
- Forward collision alert disabled
- Cruise control limited to non-adaptive mode
- Warning message on dash
Common causes
- Radar/lidar unit failure
- Sensor blocked by dirt or ice
- Wiring damage to sensor
- Control module failure
Diagnostic steps
- Clean sensor face (radar cover or camera lens)
- Check for obstructions in front of sensor
- Test sensor power supply
- Inspect wiring and connector
- Perform sensor self-test with scan tool
Repair notes
Clean sensor area first. Replace radar/lidar unit if internal failure.
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