B0104high severityBody
Immobilizer Control Module Communication
on 2003 Audi A4 3.0L V6 · AWD
What this code means
The immobilizer control module is not communicating with the ECM/PCM. Both modules must agree before engine starting is allowed.
Symptoms
- Engine will not start
- Security light on
- No communication with immobilizer module
- Multiple no-start codes
Common causes
- Immobilizer module failure
- CAN bus wiring issue between modules
- ECM/PCM fault
- Power or ground issue to immobilizer module
Diagnostic steps
- Check CAN bus communication
- Test immobilizer module power and ground
- Scan both immobilizer and ECM for codes
- Check wiring between modules
- Try key relearn procedure
Repair notes
Repair CAN bus wiring or replace immobilizer control module. Modules may need to be paired.
Other Body codes on this vehicle
B0001
Driver Frontal Stage 1 Deployment Control
B0002
Driver Frontal Stage 2 Deployment Control
B0003
Passenger Frontal Stage 1 Deployment Control
B0004
Passenger Frontal Stage 2 Deployment Control
B0005
Driver Knee Airbag Deployment Circuit
B0006
Passenger Knee Airbag Deployment Circuit
B0010
Driver Side Airbag Deployment
B0011
Driver Side Airbag Deployment Circuit Open
B0012
Driver Side Airbag Deployment Circuit Short to Ground
B0013
Driver Side Airbag Deployment Circuit Short to Battery