U0128critical severityNetwork
Lost Communication with Brake Boost Control Module
on 2011 Subaru Legacy 3.6L H6 · AWD
What this code means
Cannot communicate with the power brake booster control module on vehicles with electric brake boost.
Symptoms
- Brake pedal feels hard
- Brake boost warning light
- Increased stopping distance
- Brake assist not available
Common causes
- Electric brake booster module failure
- CAN bus wiring
- Module power loss
- Fuse blown
- Brake booster motor failure
Diagnostic steps
- Check brake booster module fuse
- Test module power and ground
- Check CAN wiring
- Test brake booster motor
- Check brake fluid level
Repair notes
Safety critical. Brakes still function but with no power assist. Check fuses and power supply.
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