B0102high severityBody
Immobilizer Transponder Authentication Failure
on 2025 Fiat Cronos 1.3L I4 Flex Firefly · FWD
What this code means
The immobilizer detected a transponder signal but authentication failed. The key code does not match the stored code.
Symptoms
- Engine cranks but will not start
- Security light solid on
- Key rejected by system
Common causes
- Key not programmed to this vehicle
- Immobilizer module lost key memory
- Aftermarket key with incorrect code
- Immobilizer control module failure
Diagnostic steps
- Try all registered keys
- Check key programming status
- Attempt key relearn procedure
- Scan immobilizer module codes
- Verify VIN match in immobilizer
Repair notes
Reprogram key to vehicle using manufacturer procedure. May require dealer tool.
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