U0302high severityNetwork
Software Incompatibility with TCM
on 2003 Subaru Legacy 3.0L H6 · AWD
What this code means
The data from the Transmission Control Module is incompatible or corrupted.
Symptoms
- Transmission shift problems
- Harsh shifting
- Check Engine Light
- Transmission warning light
Common causes
- TCM software mismatch
- TCM programming incomplete
- Wrong TCM calibration
- TCM-ECM version conflict
Diagnostic steps
- Check TCM software version
- Compare ECM and TCM software compatibility
- Reprogram TCM
- Check for TSBs
- Verify correct calibration file
Repair notes
Reprogram TCM with correct calibration that matches the ECM software version.
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