Subaru Legacy IV (2008 year). Manual - part 570

EN(H6DO)(diag)-253

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

8

CHECK CANISTER.

Is the canister damaged or is 
there a hole of more than 
0.5 mm (0.020 in) dia. in it?

Repair or replace 
the canister. <Ref. 
to EC(H6DO)-6, 
Canister.>

Go to step 9.

9

CHECK FUEL TANK.
Remove the fuel tank. <Ref. to FU(H6DO)-45, 
Fuel Tank.>

Is the fuel tank damaged or is 
there any hole of more than 
0.5 mm (0.020 in) dia. in it?

Repair or replace 
the fuel tank. <Ref. 
to FU(H6DO)-45, 
Fuel Tank.>

Go to step 10.

10

CHECK ANY OTHER MECHANICAL TROU-
BLE IN EVAPORATIVE EMISSION CON-
TROL SYSTEM.

Is there any hole of more than 
0.5 mm (0.020 in) dia., crack, 
clogging, or disconnections, 
bend, misconnection of hoses 
or pipes in evaporative emis-
sion control system?

Repair or replace 
the hoses or pipes.

Repair the poor 
contact of ECM 
connector.

Step

Check

Yes

No

EN(H6DO)(diag)-254

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CK:DTC P0457 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED 

(FUEL CAP LOOSE/OFF)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-133, DTC P0457 EVAPORATIVE EMISSION CONTROL
SYSTEM LEAK DETECTED (FUEL CAP LOOSE/OFF), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Fuel odor
• Fuel filler cap loose or lost

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:

SBF-7

E4

B47

E

5
3

6
4

2
1

ECM

2

1

C17

C28

D29

R15

R213

R68

R144

R1

B97

14

7

2

2

1

1

15

1

5

PURGE CONTROL

SOLENOID VALVE

DRAIN VALVE

PRESSURE CONTROL 

SOLENOID VALVE

MAIN RELAY

R68

E4

1 2

B47

3

4

1

2

5

6

R144

1 2

R213

1 2

3

4 5 6 7 8

R67

1

2

3 4 5 6

B97

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

R46

R67

6

BATTERY

B21

E2

E76

E77

41

48

2

10

E77

1

3

4 5 6

2

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

B136

C:

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

D:

B136

C:

B137

D:

EN-06878

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)-255

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FUEL FILLER CAP.
1) Turn the ignition switch to OFF.
2) Check the fuel filler cap.

NOTE:
The DTC is stored in memory if fuel filler cap is
or was loose or if the cap chain has caught while
tightening.

Is the fuel filler cap tightened 
securely?

Go to step 2.

Tighten fuel filler 
cap securely.

2

CHECK FUEL FILLER CAP.

Is the fuel filler cap genuine?

Go to step 3.

Replace with a 
genuine fuel filler 
cap.

3

CHECK FUEL FILLER PIPE GASKET.

Is there any damage to the seal 
between fuel filler cap and fuel 
filler pipe?

Repair or replace 
the fuel filler cap 
and fuel filler pipe. 
<Ref. to 
FU(H6DO)-52,
Fuel Filler Pipe.>

Go to step 4.

4

CHECK DRAIN VALVE.
1) Connect the delivery (test) mode connector.
2) Turn the ignition switch to ON.
3) Operate the drain valve using the Subaru 
Select Monitor.

NOTE:
Drain valve can be operated using the Subaru
Select Monitor. For the procedures, refer to
“Compulsory Valve Operation Check Mode”.
<Ref. to EN(H6DO)(diag)-53, Compulsory
Valve Operation Check Mode.>

Does the drain valve operate?

Go to step 5.

Replace the drain 
valve. <Ref. to 
EC(H6DO)-16,
Drain Valve.>

5

CHECK PURGE CONTROL SOLENOID 
VALVE.
Operate the purge control solenoid valve using 
the Subaru Select Monitor.

NOTE:
Purge control solenoid valve operation can be
executed using Subaru Select Monitor. For the
procedures, refer to “Compulsory Valve Opera-
tion Check Mode”. <Ref. to EN(H6DO)(diag)-
53, Compulsory Valve Operation Check
Mode.>

Does the purge control sole-
noid valve operate?

Go to step 6.

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

6

CHECK PRESSURE CONTROL SOLENOID 
VALVE.
Operate the pressure control solenoid valve 
using the Subaru Select Monitor.

NOTE:
The pressure control solenoid valve operation
can be executed using the Subaru Select Mon-
itor. For the procedures, refer to “Compulsory
Valve Operation Check Mode”. <Ref. to
EN(H6DO)(diag)-53, Compulsory Valve Opera-
tion Check Mode.>

Does the pressure control sole-
noid valve operate?

Go to step 7.

Replace the pres-
sure control sole-
noid valve. <Ref. to 
EC(H6DO)-13,
Pressure Control 
Solenoid Valve.>

7

CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM LINE.
1) Turn the ignition switch to OFF.
2) Disconnect the delivery (test) mode connec-
tor.

Are there any disconnected, 
broken or clogged evaporation 
lines?

Repair or replace 
the evaporation 
line. <Ref. to 
FU(H6DO)-65,
Fuel Delivery and 
Evaporation 
Lines.>

Go to step 8.

EN(H6DO)(diag)-256

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

8

CHECK CANISTER.

Is the canister damaged?

Repair or replace 
the canister. <Ref. 
to EC(H6DO)-6, 
Canister.>

Go to step 9.

9

CHECK FUEL TANK.
Remove the fuel tank. <Ref. to FU(H6DO)-45, 
Fuel Tank.>

Is the fuel tank damaged?

Repair or replace 
the fuel tank. <Ref. 
to FU(H6DO)-45, 
Fuel Tank.>

Go to step 10.

10

CHECK ANY OTHER MECHANICAL TROU-
BLE IN EVAPORATIVE EMISSION CON-
TROL SYSTEM.

Are there holes, cracks, clog-
ging, or disconnections, mis-
connection of hoses or pipes in 
evaporative emission control 
system?

Repair or replace 
the hoses or pipes.

Repair the poor 
contact of ECM 
connector.

Step

Check

Yes

No