Subaru Legacy 2004 Service Manual page 3202

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
11 CHECK OTHER DTC DETECTION.
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
Check
Is any other DTC displayed?
VDC(diag)-129
Yes
Perform the diag- Temporary poor
nosis according to contact occurs.
DTC.
No