U0420moderate severityNetwork
Invalid Data Received from Ride Level Control Module
on 2004 Subaru Legacy 3.0L H6 · AWD
What this code means
Data from the air suspension or ride height control module is corrupted.
Symptoms
- Suspension warning light
- Incorrect ride height
- Vehicle listing to one side
- Compressor cycling abnormally
Common causes
- Height sensor calibration lost
- CAN bus noise
- Module sending incorrect data
- Sensor wiring issue
Diagnostic steps
- Check ride height sensor readings
- Recalibrate suspension module
- Test CAN bus quality
- Inspect height sensor wiring
- Compare actual vs reported ride height
Repair notes
Recalibrate ride height sensors. Check sensor wiring at each corner.
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