B0040critical severityBody
Front Crash Sensor Communication Error
on 2013 Audi A6 3.0L Supercharged V6 · AWD
What this code means
Communication loss between the front crash sensor and the airbag control module over the dedicated sensor bus.
Symptoms
- Airbag warning light on
- SRS fault stored
- Frontal protection may be degraded
Common causes
- Damaged sensor bus wiring
- Faulty front crash sensor
- ACM internal fault
- Connector pin damage
Diagnostic steps
- Scan SRS codes for communication faults
- Inspect sensor bus wiring
- Check connector pins
- Test sensor power and ground
- Attempt ACM-to-sensor communication test
Repair notes
Repair sensor bus wiring or replace front crash sensor.
Other Body codes on this vehicle
B0001
Driver Frontal Stage 1 Deployment Control
B0001
Driver Frontal Stage 1 Deployment Control
B0002
Driver Frontal Stage 2 Deployment Control
B0002
Driver Frontal Stage 2 Deployment Control
B0003
Passenger Frontal Stage 1 Deployment Control
B0003
Passenger Frontal Stage 1 Deployment Control
B0004
Passenger Frontal Stage 2 Deployment Control
B0004
Passenger Frontal Stage 2 Deployment Control
B0005
Driver Knee Airbag Deployment Circuit
B0005
Driver Knee Airbag Deployment Circuit