Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 258

EN(H4DOTC)(diag)-256

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CH:DTC P0451 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/

SWITCH RANGE/PERFORMANCE

DTC DETECTING CONDITION:

• Detected when 2 consecutive driving cycles with fault occur.

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-155, DTC P0451 EVAPORATIVE EMISSION SYS-

TEM PRESSURE SENSOR/SWITCH RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting

Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

Step

Check

Yes

No

1

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

Check the appropri-
ate DTC using the
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)(diag)
-87, List of Diagnos-
tic Trouble Code
(DTC).>

Go to step

2.

2

CHECK CURRENT DATA.
1) Turn the ignition switch to ON (engine OFF).
2) Using the Subaru Select Monitor or general
scan tool, read the value in «Atmosphere Pres-
sure» and «Mani. Absolute Pressure», and
compare them with the actual atmospheric
pressure.
NOTE:

• Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-40, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
• To read the actual atmospheric pressure,
connect the Subaru Select Monitor or general
scan tool to the other known good vehicle.

Is the difference with the actual
atmospheric pressure 3.3 kPa
(24.5 mmHg, 1 inHg) or more?

Replace the part
that showed larger
deviation from the
actual atmospheric
pressure than the
other.
• If deviations in
value for «Atmo-
sphere Pressure»
is larger: Replace
the leak check
valve assembly.
<Ref. to EC(STI)-
19, Leak Check
Valve Assembly.>
<Ref. to EC(w/o
STI)-20, Leak
Check Valve
Assembly.>
• If deviations in
value for «Mani.
Absolute Pres-
sure» is larger:
Replace the mani-
fold absolute pres-
sure sensor. <Ref.
to FU(STI)-43,
Manifold Absolute
Pressure Sen-
sor.> <Ref. to
FU(w/o STI)-43,
Manifold Absolute
Pressure Sensor.>

Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:

In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.

EN(H4DOTC)(diag)-257

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CI: DTC P0452 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/

SWITCH LOW

DTC DETECTING CONDITION:

• Immediately at fault recognition

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-157, DTC P0452 EVAPORATIVE EMISSION SYS-

TEM PRESSURE SENSOR/SWITCH LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

WIRING DIAGRAM:

• Engine electrical system, without SI-DRIVE <Ref. to WI-32, WITHOUT SI-DRIVE, WIRING DIAGRAM,

Engine Electrical System.>

• Engine electrical system, with SI-DRIVE <Ref. to WI-48, WITH SI-DRIVE, WIRING DIAGRAM, Engine

Electrical System.>

ECM

B97

R1

10

B92

2 3 4 5

6 7 8 9

11 12 13 14

17 18 19 20

1

10

15 16

B97

R82

1 2

3 4 5

6 7 8 9 10 11 12

B220

B83

4

1 2 3

6

5

*

B83

*

*

D27

B22

C21

B30

B4

B135

B:

B136

C:

B137

D:

14

17

15

16

13

8

R81

R82

1

5

8

7

6

4

3

R400

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

B135

B:

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

B137

D:

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:

1 2

4

5 6 7 8

3

R400

24

23

22

21

B220

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32 35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

B220

4

3

EN-09250

R5

B92

E

SBF-7

BATTERY

FUSE

(RELAY BLOCK)

MAIN RELAY

LEAK CHECK VALVE ASSY

VACUUM

PUMP

PRESSURE

SENSOR

SWITCHING

VALVE

: TERMINAL No. OPTIONAL ARRANGEMENT

EN(H4DOTC)(diag)-258

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «Atmosphere Pressure»
using the Subaru Select Monitor or a general
scan tool.
NOTE:

• Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-40, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the value in «Atmosphere
Pressure» 34 kPa (255 mmHg,
10 inHg) or less?

Go to step

2.

Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:

In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.

2

CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.

Connector & terminal

(R400) No. 6 (+) — Chassis ground (–):

Is the voltage 4.5 V or more?

Go to step

3.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and the leak check
valve

assembly

connector
• Poor contact of
ECM connector
• Poor contact of
coupling connector

3

CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and chassis ground.

Connector & terminal

(B136) No. 21 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

4.

Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.

4

CHECK FOR POOR CONTACT.
Check for poor contact of leak check valve
assembly connector.

Is there poor contact in the leak
check valve assembly connec-
tor?

Repair the poor
contact in the leak
check valve
assembly connec-
tor.

Replace the leak
check valve
assembly. <Ref. to
EC(STI)-19, Leak
Check Valve
Assembly.> <Ref.
to EC(w/o STI)-20,
Leak Check Valve
Assembly.>

EN(H4DOTC)(diag)-259

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CJ:DTC P0453 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/

SWITCH HIGH

DTC DETECTING CONDITION:

• Immediately at fault recognition

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-159, DTC P0453 EVAPORATIVE EMISSION SYS-

TEM PRESSURE SENSOR/SWITCH HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

WIRING DIAGRAM:

• Engine electrical system, without SI-DRIVE <Ref. to WI-32, WITHOUT SI-DRIVE, WIRING DIAGRAM,

Engine Electrical System.>

• Engine electrical system, with SI-DRIVE <Ref. to WI-48, WITH SI-DRIVE, WIRING DIAGRAM, Engine

Electrical System.>

ECM

B97

R1

10

B92

2 3 4 5

6 7 8 9

11 12 13 14

17 18 19 20

1

10

15 16

B97

R82

1 2

3 4 5

6 7 8 9 10 11 12

B220

B83

4

1 2 3

6

5

*

B83

*

*

D27

B22

C21

B30

B4

B135

B:

B136

C:

B137

D:

14

17

15

16

13

8

R81

R82

1

5

8

7

6

4

3

R400

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

B135

B:

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

B137

D:

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:

1 2

4

5 6 7 8

3

R400

24

23

22

21

B220

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32 35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

B220

4

3

EN-09250

R5

B92

E

SBF-7

BATTERY

FUSE

(RELAY BLOCK)

MAIN RELAY

LEAK CHECK VALVE ASSY

VACUUM

PUMP

PRESSURE

SENSOR

SWITCHING

VALVE

: TERMINAL No. OPTIONAL ARRANGEMENT