Subaru Legacy III (2000-2003 year). Manual — part 351

EN(H6DO)-206

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

13

CHECK STATUS OF CHECK ENGINE MAL-
FUNCTION INDICATOR LAMP (MI).
1) Clear memory using Subaru Select Moni-

tor.
<Ref. to EN(H6DO)-54, Clear Memory
Mode.>

2) Start engine, and drive the vehicle more

than 10 minutes.
Is the MI coming on or blinking?

Comes on or blinking.

Go to step 15.

Go to step 14.

14

CHECK CAUSE OF MISFIRE DIAGNOSED.
Was the cause of misfire diagnosed when the
engine is running?

Diagnosed.

Finish diagnostics
operation, if the
engine has no
abnormality.

Repair poor con-
tact.

NOTE:
In this case, repair
the following:
• Poor contact in
ignition coil con-
nector
• Poor contact in
fuel injector con-
nector on faulty
cylinders
• Poor contact in
ECM connector
• Poor contact in
coupling connector

15

CHECK AIR INTAKE SYSTEM.
Is there a fault in air intake system?

There is a malfunction.

Repair air intake
system.

NOTE:
Check the follow-
ing items:
• Are there air
leaks or air suction
caused by loose or
dislocated nuts
and bolts?
• Are there cracks
or any disconnec-
tion of hoses?

Go to step 16.

16

CHECK MISFIRE SYMPTOM.
1) Turn ignition switch to ON.
2) Read diagnostic trouble code (DTC) using

the Subaru Select Monitor or OBD-II gen-
eral scan tool.

• Subaru Select Monitor
<Ref. to EN(H6DO)-34, Subaru Select Moni-
tor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.

Does the Subaru Select Monitor or OBD-II
general scan tool indicate only one DTC?

Only one DTC is indicated.

Go to step 22.

Go to step 17.

17

CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0301 and
P0302?

Indicated.

Go to step 23.

Go to step 18.

Step

Value

Yes

No

EN(H6DO)-207

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

18

CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0303 and
P0304?

Indicated.

Go to step 24.

Go to step 19.

19

CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0305 and
P0306?

Indicated.

Go to step 25.

Go to step 20.

20

CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0301, P0303
and P0305?

Indicated.

Go to step 26.

Go to step 21.

21

CHECK DIAGNOSTIC TROUBLE CODE
(DTC) ON DISPLAY.
Does the Subaru Select Monitor or OBD-II
general scan tool indicate DTC P0302, P0304
and P0306?

Indicated.

Go to step 27.

Go to step 28.

22

ONLY ONE CYLINDER
Is there a fault in that cylinder?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plug
• Fuel injector
• Compression
ratio

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

23

GROUP OF #1 AND #2 CYLINDERS
Are there faults in #1 and #2 cylinders?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
• Check the follow-
ing items.
Spark plugs
Fuel injectors
Ignition coil
Compression ratio
• If no abnormality
is discovered,
check for “IGNI-
TION CONTROL
SYSTEM” of #1
and #2 cylinders
side. <Ref. to
EN(H6DO)-80,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Failure.>

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

Step

Value

Yes

No

EN(H6DO)-208

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

24

GROUP OF #3 AND #4 CYLINDERS
Are there faults in #3 and #4 cylinders?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
• Check the follow-
ing items.
Spark plugs
Fuel injectors
Ignition coil
• If no abnormality
is discovered,
check for “17. D:
IGNITION CON-
TROL SYSTEM”
of #3 and #4 cylin-
ders side. <Ref. to
EN(H6DO)-80,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Failure.>

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

25

GROUP OF #5 AND #6 CYLINDERS
Are there faults in #5 and #6 cylinders?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
• Check the fol-
lowing items:
Spark plugs, fuel
injector, ignition
coil and compres-
sion ratio
• If no abnormality
is discovered,
check for “17.
IGNITION CON-
TROL SYSTEM”
of #5 and #6 cylin-
ders side. <Ref. to
EN(H6DO)-80,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Failure.>

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

26

GROUP OF #1, #3 AND #5 CYLINDERS
Are there faults in #1, #3 and #5 cylinders?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plugs
• Fuel injectors
• Skipping timing
chain

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

Step

Value

Yes

No

EN(H6DO)-209

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

27

GROUP OF #2, #4 AND #6 CYLINDERS
Are there faults in #2, #4 and #6 cylinders?

There is a malfunction.

Repair or replace
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plugs
• Fuel injectors
• Compression
ratio
• Skipping timing
chain

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

28

CYLINDER AT RANDOM
Is the engine idle unstable?

Engine idle is unstable.

Inspect DTC
P0171, P0172,
P0174 or P0175
using “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

Repair or replace
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plugs
• Fuel injectors
• Compression
ratio

Step

Value

Yes

No