U0129critical severityNetwork
Lost Communication with Brake System Control Module
on 2019 Mazda Mazda3 2.5L I4 · FWD
What this code means
Cannot communicate with the general brake system control module.
Symptoms
- Brake warning light on
- ABS disabled
- Stability control off
- Brake system message displayed
Common causes
- Brake module failure
- CAN bus wiring damage
- Module power loss
- Fuse blown
- Water damage
Diagnostic steps
- Check brake system fuses
- Test module power and ground
- Check CAN wiring
- Inspect module for water damage
- Try direct module communication
Repair notes
Check fuses and power supply. Inspect for water damage near brake module location.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus