Subaru Impreza 2004 Service Manual page 207

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK ANY OTHER DTC.
Conduct the troubleshooting for all DTC
P0301, P0302, P0303 and P0304. <Ref. to
EN(H4DOTC)(diag)-74, List of Diagnostic
Trouble Code (DTC).>
Check
Does failure for repair or
replacement exist?
EN(H4DOTC)(diag)-286
Yes
Repair or replace Contact your Sub-
the failure, then aru distributor ser-
replace precata- vice.
lytic converter.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
No
be-
probable
multiple