B0100high severityBody
Immobilizer System General Malfunction
on 2021 Audi S5 3.0L Turbo V6 · AWD
What this code means
A general fault detected in the engine immobilizer system. The immobilizer prevents engine starting without a recognized key or transponder.
Symptoms
- Engine cranks but will not start
- Security/immobilizer warning light on
- Key not recognized
- Intermittent no-start condition
Common causes
- Faulty key transponder
- Immobilizer antenna ring failure
- Immobilizer control module fault
- Key not programmed to vehicle
- Weak key battery
Diagnostic steps
- Try spare key
- Check immobilizer warning light pattern
- Scan immobilizer module for specific codes
- Test transponder ring antenna
- Verify key programming status
Repair notes
Try spare key first. Reprogram key to immobilizer if needed. Replace antenna ring or immobilizer module if faulty.
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
B0007
Rear Left Side Airbag Deployment Circuit
B0008
Rear Right Side Airbag Deployment Circuit
B0009
Rear Center Airbag Deployment Circuit
B0010
Driver Side Airbag Deployment