U0121high severityNetwork
Lost Communication with ABS Module
on 2004 Subaru Baja 2.5L H4 Turbo · AWD
What this code means
Cannot communicate with the Anti-lock Brake System module.
Symptoms
- ABS light on
- Traction control disabled
- Stability control disabled
Common causes
- ABS module power failure
- CAN bus wiring
- ABS module failure
- Fuse blown
Diagnostic steps
- Check ABS fuses
- Test module power and ground
- Check CAN wiring
- Try direct communication
Repair notes
Check fuses first. Common on water-damaged vehicles.
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