Subaru Legacy 2003 Service Manual page 570

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
16 CHECK MISFIRE SYMPTOM.
1) Turn ignition switch to ON.
2) Read diagnostic trouble code (DTC).
Does the Subaru Select Monitor or OBD-II
general scan tool indicate only one DTC?
•Subaru Select Monitor
<Ref. to EN(H4SO)-32, Subaru Select Moni-
tor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
NOTE:
Perform diagnosis according to the items listed
below.
17 CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0301 and
P0302?
18 CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0303 and
P0304?
19 CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0301 and
P0303?
20 CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0302 and
P0304?
21 ONLY ONE CYLINDER
Is there any fault in that cylinder?
Value
Only one DTC indicated.
DTC P0301 and P0302 indi-
cated.
DTC P0303 and P0304 indi-
cated.
DTC P0301 and P0303 indi-
cated.
DTC P0302 and P0304 indi-
cated.
There is a fault.
EN(H4SO)-173
ENGINE (DIAGNOSTICS)
Yes
Go to step 21. Go to step 17.
Go to step 22. Go to step 18.
Go to step 23. Go to step 19.
Go to step 24. Go to step 20.
Go to step 25. Go to step 26.
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to
EN(H4SO)-162,
NOTE:
DTC P0171 —
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1) —
• Spark plug
, Diagnostic Pro-
• Spark plug cord
cedure with Diag-
• Fuel injector
nostic Trouble
• Compression
Code (DTC).>
ratio
No