Subaru Legacy IV (2008 year). Manual - part 162

EN(H4SO)(diag)-251

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CN:DTC P1491 POSITIVE CRANKCASE VENTILATION (BLOW-BY) FUNCTION 

PROBLEM

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-167, DTC P1491 POSITIVE CRANKCASE VENTILA-
TION (BLOW-BY) FUNCTION PROBLEM, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-04049

E61

1

2

30

10

B21

E2

E

B134

E61

1 2

PCV

DIAGNOSIS 

CONNECTOR

ECM

B134

8

5

6

10 11 12 13 14 15

7

2

1

3

4

16

30

19 20

22

28 29

9

17

18

25

21

23 24

32

31

26 27
33 34

B21

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25 26 27 28 29 30 31 32 33

34

35

42

43

36

37

38

39

48

49

50

51

52

53

54

40

41

44

45

46

47

EN(H4SO)(diag)-252

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK BLOW-BY HOSE.
Check the condition of the blow-by hose.

Is there any disconnection or 
crack in blow-by hose?

Repair or replace 
the blow-by hose.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
PCV HOSE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM 
and PCV hose assembly.
3) Measure the resistance of harness between 
ECM and PCV hose assembly.

Connector & terminal

(B134) No. 30 — (E61) No. 2:

Is the resistance less than 1 

:? Go to step 3.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and PCV
hose assembly
• Poor contact of
coupling connector

3

CHECK HARNESS BETWEEN ECM AND 
PCV HOSE ASSEMBLY.
Measure the resistance between PCV hose 
assembly and chassis ground.

Connector & terminal

(B134) No. 30 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 4.

Repair the ground 
short circuit of har-
ness between 
ECM and PCV 
hose assembly.

4

CHECK GROUND CIRCUIT OF PCV HOSE 
ASSEMBLY.
Measure the resistance of harness between 
PCV hose assembly and engine ground.

Connector & terminal

(E61) No. 1 — Engine ground:

Is the resistance less than 5 

:? Go to step 5.

Repair the open 
circuit of harness 
between PCV hose 
assembly and 
engine ground.

5

CHECK THE PCV HOSE ASSEMBLY.
Measure the resistance between the PCV hose 
assembly terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 

:? Repair the poor 

contact in ECM 
and PCV hose 
assembly connec-
tor.

Replace the PCV 
hose assembly.

EN(H4SO)(diag)-253

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CO:DTC P1492 EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION 

(LOW INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)(diag)-254, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CP:DTC P1493 EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION 

(HIGH INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)(diag)-257, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CQ:DTC P1494 EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION 

(LOW INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)(diag)-254, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CR:DTC P1495 EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION 

(HIGH INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)(diag)-257, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CS:DTC P1496 EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION 

(LOW INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)(diag)-254, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CT:DTC P1497 EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION 

(HIGH INPUT)

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)(diag)-257, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

EN(H4SO)(diag)-254

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CU:DTC P1498 EGR SOLENOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION 

(LOW INPUT)

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-169, DTC P1492 EGR SOLENOID VALVE SIGNAL #1
CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Trouble Code (DTC) Detecting Criteria.> <Ref. to
GD(H4SO)-173, DTC P1494 EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION (LOW IN-
PUT), Diagnostic Trouble Code (DTC) Detecting Criteria.> <Ref. to GD(H4SO)-173, DTC P1496 EGR SO-
LENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Trouble Code (DTC)
Detecting Criteria.> <Ref. to GD(H4SO)-173, DTC P1498 EGR SOLENOID VALVE SIGNAL #4 CIRCUIT
MALFUNCTION (LOW INPUT), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Poor driving performance
• Engine breathing

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.