Subaru Legacy 2004 Service Manual page 566

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AA:DTC P0301 CYLINDER 1 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO 2.0)(diag)-135, DTC P0304 CYLIN-
DER 4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
AB:DTC P0302 CYLINDER 2 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO 2.0)(diag)-135, DTC P0304 CYLIN-
DER 4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
AC:DTC P0303 CYLINDER 3 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO 2.0)(diag)-135, DTC P0304 CYLIN-
DER 4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
EN(H4SO 2.0)(diag)-134