Subaru Legacy IV (2008 year). Manual - part 571

EN(H6DO)(diag)-257

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CL:DTC P0458 EVAPORATIVE EMISSION SYSTEM PURGE CONTROL VALVE 

CIRCUIT LOW

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-134, DTC P0458 EVAPORATIVE EMISSION SYSTEM
PURGE CONTROL VALVE CIRCUIT LOW, 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(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

E4

B47

B47

3

4

1

2

5

6

SBF-7

1

2

4

6

3

5

29

B21

E2

48

41

B137

ECM

2

1

E4

1 2

E

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

10

2

E76

E77

E77

BATTERY

MAIN RELAY

PURGE CONTROL 

SOLENOID VALVE

1 2

3 4

5

6

7

8

9

10

EN-06879

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(H6DO)(diag)-258

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B137) No. 29 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the poor 
contact of ECM 
connector.

Go to step 2.

2

CHECK IN HARNESS BETWEEN ECM AND 
PURGE CONTROL SOLENOID VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
purge control solenoid valve.
3) Measure the resistance between the purge 
control solenoid valve connector and engine 
ground.

Connector & terminal

(E4) No. 2 — Engine ground:

Is the resistance 1 M

: or 

more?

Go to step 3.

Repair the ground 
short circuit of har-
ness between 
ECM and purge 
control solenoid 
valve connector.

3

CHECK HARNESS BETWEEN ECM AND 
PURGE CONTROL SOLENOID VALVE.
Measure the resistance of harness between 
ECM and purge control solenoid valve connec-
tor.

Connector & terminal

(B137) No. 29 — (E4) No. 2:

Is the resistance less than 1 

:? Go to step 4.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and purge
control solenoid
valve connector
• Poor contact of
coupling connector

4

CHECK PURGE CONTROL SOLENOID 
VALVE.
1) Remove the purge control solenoid valve.
2) Measure the resistance between purge con-
trol solenoid valve terminals.

Terminals

No. 1 — No. 2:

Is the resistance between 10 — 
100 

:?

Go to step 5.

Replace the purge 
control solenoid 
valve. <Ref. to 
EC(H6DO)-8,
Purge Control 
Solenoid Valve.>

5

CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE.
1) Turn the ignition switch to ON.
2) Measure the voltage between purge control 
solenoid valve and engine ground.

Connector & terminal

(E4) No. 1 (+) — Engine ground (–):

Is the voltage 10 V or more?

Repair the poor 
contact of purge 
control solenoid 
valve connector.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
main relay and
purge control sole-
noid valve connec-
tor
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor

EN(H6DO)(diag)-259

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CM:DTC P0459 EVAPORATIVE EMISSION SYSTEM PURGE CONTROL VALVE 

CIRCUIT HIGH

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-136, DTC P0459 EVAPORATIVE EMISSION SYSTEM
PURGE CONTROL VALVE CIRCUIT HIGH, 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(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

E4

B47

B47

3

4

1

2

5

6

SBF-7

1

2

4

6

3

5

29

B21

E2

48

41

B137

ECM

2

1

E4

1 2

E

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

10

2

E76

E77

E77

BATTERY

MAIN RELAY

PURGE CONTROL 

SOLENOID VALVE

1 2

3 4

5

6

7

8

9

10

EN-06879

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(H6DO)(diag)-260

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND 
PURGE CONTROL SOLENOID VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
purge control solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B137) No. 29 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short 
circuit to power in 
the harness 
between ECM and 
purge control sole-
noid valve connec-
tor.

Go to step 2.

2

CHECK PURGE CONTROL SOLENOID 
VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge con-
trol solenoid valve terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 

:? Replace the purge 

control solenoid 
valve. <Ref. to 
EC(H6DO)-8, 
Purge Control 
Solenoid Valve.>

Repair the poor 
contact of ECM 
connector.