B0422high severityBody
Brake Warning Lamp Circuit
on 2021 Ford Mustang Mach-E Standard Range Dual Motor AWD · RWD
What this code means
Malfunction in the brake warning lamp circuit. This includes the parking brake and low brake fluid indicators.
Symptoms
- Brake warning light always on
- Brake light does not illuminate with parking brake
- No low-fluid warning capability
Common causes
- Faulty brake fluid level switch
- Parking brake switch failure
- Cluster lamp fault
- Wiring issue
Diagnostic steps
- Check brake fluid level
- Test parking brake switch
- Test brake fluid level switch
- Check lamp circuit
- Inspect wiring
Repair notes
Check brake fluid level first. Replace faulty switch or repair wiring.
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