Subaru Legacy III (2000-2003 year). Manual - part 512

EN(H4DOSTC)-218

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BE:DTC P1242 — 2STAGE TWIN TURBO SYSTEM (TWIN) —

• TROUBLE SYMPTOM:

• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection 
Mode.> .
• WIRING DIAGRAM:

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?

DTC indicated.

Inspect the rele-
vant DTC using 
“List of Diagnostic 
Trouble Code 
(DTC)”. <Ref. to 
EN(H4DOSTC)-
62, List of Diag-
nostic Trouble 
Code (DTC).>

Go to step 2.

2

CHECK OPERATION OF RELIEF VALVE 
CONTROL SOLENOID VALVE 2.
Operate the relief valve control solenoid valve 
2. <Ref. to EN(H4DOSTC)-36, Compulsory 
Valve Operation Check Mode.>
Does the relief valve control solenoid valve 2 
produce operating sound?

Operating sound produced.

Go to step 3.

Replace the relief 
valve control sole-
noid valve 2. <Ref. 
to IN(H4DOSTC)-
19, Solenoid Box 
Assembly.>

3

CHECK OPERATION OF EXHAUST CON-
TROL VALVE.
1) Operate the exhaust valve control solenoid 

valve. <Ref. to EN(H4DOSTC)-36, Compul-
sory Valve Operation Check Mode.>

2) Check the operation of exhaust control 

valve actuator.
Does the actuator rod operate correctly?

NOTE:

Actuator rod operates in approx. 7 second cy-
cle, and stroke is approx. 30 mm (1.18 in).

Operate correctly.

Go to step 4.

Check the exhaust 
valve control sole-
noid valve and 
vacuum hose. 
<Ref. to 
IN(H4DOSTC)-19, 
Solenoid Box 
Assembly.>

4

CHECK OPERATION OF INTAKE AIR CON-
TROL VALVE.
1) Operate the intake air valve control sole-

noid valve. <Ref. to EN(H4DOSTC)-36, 
Compulsory Valve Operation Check 
Mode.>

2) Check the operation of intake air control 

valve actuator.
Does the actuator rod operate correctly?

NOTE:

Actuator rod operates in approx. 2 second cy-
cle, and stroke is approx. 12 mm (0.47 in).

Operate correctly.

Go to step 5.

Check the intake 
valve control sole-
noid valve and 
vacuum hose. 
<Ref. to 
IN(H4DOSTC)-19, 
Solenoid Box 
Assembly.>

5

CHECK RELIEF VALVE.
1) Remove the relief valve.
2) Check the relief valve.

Is there a fault in the relief valve and hose 
routing?

There is no problem.

Go to step 6.

Replace or repair 
the relief valve and 
vacuum hose.

6

CHECK VACUUM HOSES OF EXHAUST 
VALVE CONTROL SOLENOID VALVE (POS-
ITIVE PRESSURE).
Are there cracks, stuck or improper routing on 
vacuum hose?

There is no problem.

Go to step 7.

Repair or replace 
the vacuum hoses.

EN(H4DOSTC)-219

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

7

CHECK VACUUM HOSES OF DIFFEREN-
TIAL PRESSURE SENSOR.
Are there cracks, stuck or improper routing on 
vacuum hose?

There is no problem.

Go to step 8.

Repair or replace 
the vacuum hoses.

8

CHECK VACUUM HOSES OF PRIMARY 
TURBOCHARGER WASTEGATE CONTROL 
VALVE.
Are there cracks, stuck or improper routing on 
vacuum hose?

There is no problem.

Go to step 9.

Repair or replace 
the vacuum hoses.

9

CHECK VACUUM HOSES BETWEEN SOLE-
NOID BOX AND SURGE TANK.
Are there cracks, stuck or improper routing on 
vacuum hose?

There is no problem.

Go to step 10.

Repair or replace 
the vacuum hoses.

10

CHECK PRIMARY TURBOCHARGER 
WASTEGATE VALVE.
Is there a fault on the primary turbocharger 
wastegate valve?

There is no problem.

Go to step 11.

Replace the pri-
mary turbo-
charger. <Ref. to 
IN(H4DOSTC)-15, 
Turbocharger.>

11

CHECK LH AND RH INTAKE DUCT.
Are there cracks or stuck on the LH and RH 
intake duct?

There is no problem.

Replace the ECM. 
<Ref. to 
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

Replace the air 
intake duct. <Ref. 
to IN(H4DOSTC)-
12, Intake Duct.>

Step

Value

Yes

No

EN(H4DOSTC)-220

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BF:DTC P1247 — RELIEF VALVE CONTROL SOLENOID VALVE 1 CIRCUIT LOW 

—

• TROUBLE SYMPTOM:

• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00939

B220

B47

E

BATTERY

MAIN RELAY

3

B136

ECM

SBF-5

5

2
1

4

6

B47

3

4

1

2

5

6

B220

SOLENOID 
BOX ASSY

1

2

3

4

5

6

7

8

9

10

11

12

(A)

(B)

(C)

(D)

(E)

(F)

(A): RELIEF VALVE SOLENOID 2
(B): RELIEF VALVE SOLENOID 1
(C): EXHAUST VALVE CONTROL SOLENOID VALVE
       (NEGATIVE PRESSURE)
(D): EXHAUST VALVE CONTROL SOLENOID VALVE
       (POSITIVE PRESSURE)
(E): INTAKE AIR CONTROL SOLENOID VALVE
(F): EXHAUST VALVE CONTROL DUTY SOLENOID VALVE

C:

B137

D:

C11

C12

C3

C1

D22

D11

1 2 3 4
5 6 7 8
9 10 11 12

B136

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

B137

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

EN(H4DOSTC)-221

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK INPUT SIGNAL TO ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and 

chassis ground.

Connector & terminal

(B136) No. 12 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Even if MI lights 
up, the circuit has 
returned to a nor-
mal condition at 
this time. Contact 
with your Subaru 
distributor.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

Go to step 2.

2

CHECK HARNESS BETWEEN RELIEF 
VALVE CONTROL SOLENOID VALVE 1 AND 
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from relief valve 

control solenoid valve 1 and ECM.

3) Measure the resistance of harness 

between relief valve control solenoid valve 
1 connector and engine ground.

Connector & terminal

(B220) No. 4 — Engine ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 3.

Repair the ground 
short circuit in har-
ness between 
ECM and relief 
valve control sole-
noid valve 1 con-
nector.

3

CHECK HARNESS BETWEEN RELIEF 
VALVE CONTROL SOLENOID VALVE 1 AND 
ECM CONNECTOR.
Measure the resistance of harness between 
ECM and relief valve control solenoid valve 1 
of harness connector.

Connector & terminal

(B136) No. 12 — (B220) No. 4:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 4.

Repair the open 
circuit in harness 
between ECM and 
relief valve control 
solenoid valve 1 
connector.

4

CHECK RELIEF VALVE CONTROL SOLE-
NOID VALVE 1.
Measure the resistance between relief valve 
control solenoid valve 1 terminals.

Terminals

No. 3 — No. 4:

Is the measured value within the specified 
value?

37 — 44 

Ω

Go to step 5.

Replace the relief 
valve control sole-
noid valve 1.  
<Ref. to 
IN(H4DOSTC)-19, 
Solenoid Box 
Assembly.>

5

CHECK POWER SUPPLY TO RELIEF VALVE 
CONTROL SOLENOID VALVE 1.
1) Turn the ignition switch to ON.
2) Measure the voltage between relief valve 

control solenoid valve 1 and engine ground.

Connector & terminal

(B220) No. 3 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 6.

Repair the open 
circuit in harness 
between main 
relay and relief 
valve control sole-
noid valve 1 con-
nector.