Theft Deterrent System Malfunction
2018-2025 Fiat Cronos 1.3L I4 Flex Firefly
Description
A general fault in the vehicle theft deterrent (anti-theft) system. The system may trigger false alarms or not arm properly.
Symptoms
- Security light flashing rapidly
- False alarm activation
- System will not arm
- Horn chirp confirmation missing when locking
Common Causes
- Faulty hood/door/trunk switch
- BCM anti-theft module failure
- Wiring issue
- Aftermarket alarm interfering
- Battery was disconnected
Diagnostic Steps
- Scan BCM for theft deterrent codes
- Check all door, hood, and trunk switches
- Inspect for aftermarket alarm system
- Verify BCM programming
- Test alarm arm/disarm cycle
Repair Notes
Repair faulty switches or wiring. Remove conflicting aftermarket alarm if present.
Related Codes
Other Body Codes
- B0001Driver Frontal Stage 1 Deployment Control
- B0002Driver Frontal Stage 2 Deployment Control
- B0003Passenger Frontal Stage 1 Deployment Control
- B0004Passenger Frontal Stage 2 Deployment Control
- B0005Driver Knee Airbag Deployment Circuit
- B0006Passenger Knee Airbag Deployment Circuit
- B0007Rear Left Side Airbag Deployment Circuit
- B0008Rear Right Side Airbag Deployment Circuit
- B0009Rear Center Airbag Deployment Circuit
- B0010Driver Side Airbag Deployment
B0120 on Other Vehicles
Fiat 124 Spider
2017-2020 1.4L I4 Turbo
Fiat 126p Maluch
1973-2000 0.65L I2 Air-Cooled
Fiat 126p Maluch
1987-2000 0.7L I2 Air-Cooled
Fiat 500
2012-2019 1.4L I4
Fiat 500 Abarth
2012-2019 1.4L I4 Turbo
Fiat 500 BR
2011-2020 1.4L I4 Flex Fire Evo
Fiat 500 PL
2007-2025 1.0L I3 Hybrid FireFly 70
Fiat 500 PL
2007-2025 1.2L I4 Fire 69
Common Questions
What does code B0120 mean on a 2018-2025 Fiat Cronos?
B0120 stands for "Theft Deterrent System Malfunction". A general fault in the vehicle theft deterrent (anti-theft) system. The system may trigger false alarms or not arm properly.
What are the symptoms of B0120 on a Fiat Cronos?
Common symptoms of B0120 include: Security light flashing rapidly, False alarm activation, System will not arm, Horn chirp confirmation missing when locking.
What causes B0120 on a 2018-2025 Fiat Cronos?
Common causes of B0120 include: Faulty hood/door/trunk switch, BCM anti-theft module failure, Wiring issue, Aftermarket alarm interfering, Battery was disconnected.