Subaru Legacy IV (2008 year). Service manual — part 150

EN(H4SO)(diag)-203

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

BH:DTC P0448 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL

CIRCUIT SHORTED

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-119, DTC P0448 EVAPORATIVE EMISSION CONTROL
SYSTEM VENT CONTROL CIRCUIT SHORTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>

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-06841

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

17

B97

R1

1

2

7

R144

R15

R213

R46

R67

ECM

B136

SBF-7

5
3

6
4

2
1

B47

6

1

E

DRAIN
VALVE

MAIN RELAY

BATTERY

B47

3

4

1

2

5

6

1 2

3

4 5 6 7 8

1

2

3 4 5 6

R67

R213

B97

14

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

1 2

R144

EN(H4SO)(diag)-204

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND
DRAIN VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and drain valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.

Connector & terminal

(B136) No. 17 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to the power
supply in the har-
ness between the
ECM and drain
valve connector.

Go to step 2.

2

CHECK DRAIN VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between drain valve
terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 1

:? Replace the drain

valve. <Ref. to
EC(H4SO)-16,
Drain Valve.>

Repair the poor
contact of ECM
connector.

EN(H4SO)(diag)-205

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

BI: DTC P0451 EVAPORATIVE EMISSION CONTROL SYSTEM PRESSURE

SENSOR

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-121, DTC P0451 EVAPORATIVE EMISSION CONTROL
SYSTEM PRESSURE SENSOR, Diagnostic Trouble Code (DTC) Detecting Criteria.>

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-05047

6

17

13

B97

R1

7

6

4

R15

R213

3

2

1

R47

B83

B135 ECM

B97

B83

3 4

5 6

1 2

7 8

B135

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17 18 19

20 21

29 30 31

32 33

34 35

*

*

*

R47

1 2 3

R213

1 2

3

4 5 6 7 8

22

32

30

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

FUEL TANK
PRESSURE

SENSOR

: TERMINAL No. OPTIONAL

ARRANGEMENT

EN(H4SO)(diag)-206

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) Open the fuel flap.

Is the fuel filler cap tightened
securely?

Go to step 2.

Tighten fuel filler
cap securely.

2

CHECK PRESSURE VACUUM LINE.

NOTE:
Check the following items.
• Disconnection, leakage and clogging of the
vacuum hoses and pipes between fuel tank
pressure sensor and fuel tank
• Disconnection, leakage and clogging of the
air ventilation hoses and pipes between fuel fill-
er pipe and fuel tank

Is there any fault in pressure/
vacuum line?

Repair or replace
the hoses and
pipes.

Replace the fuel
tank pressure sen-
sor. <Ref. to
EC(H4SO)-12,
Fuel Tank Pres-
sure Sensor.>