Subaru Legacy IV (2008 year). Manual - part 128

 

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Subaru Legacy IV (2008 year). Manual - part 128

 

 

EN(H4SO)(diag)-115

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

O: DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT HIGH INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-29, DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT
HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Engine stalls.
• Poor driving performance

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-06837

E

B83

3

B3

ECM

B135

SBF-7

*

*

4

1

5

2

34

18

26

30

35

B47

1

2

4

6

3

5

BATTERY

MASS AIR FLOW 

& INTAKE AIR 

TEMPERATURE 

SENSOR

MAIN RELAY

: TERMINAL No. OPTIONAL 

ARRANGEMENT

*

B3

1 2 3 4 5

3

4

1

2

5

6

B47

1 2 3 4
5 6 7 8

B83

B135

5

6

7

2

1

3

4

29

10 11 12 13 14 15

25

24

16

30

9

8

17 18 19

20
28

21 22 23

32

31

26 27

33

34 35

EN(H4SO)(diag)-116

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of air flow sensor signal using 
Subaru Select Monitor or general scan tool.

NOTE:
• SUBARU SELECT MONITOR
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO)(diag)-33, Subaru Select Moni-
tor.>
• General Scan Tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the voltage 5 V or more?

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
may be the cause.

2

CHECK HARNESS BETWEEN ECM AND 
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the mass air 
flow and intake air temperature sensor.
3) Start the engine.
4) Read the data of air flow sensor signal using 
Subaru Select Monitor or general scan tool.

NOTE:
• SUBARU SELECT MONITOR
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO)(diag)-33, Subaru Select Moni-
tor.>
• General Scan Tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the voltage 5 V or more?

Repair the short 
circuit to power in 
the harness 
between the ECM 
and the mass air 
flow and intake air 
temperature sen-
sor connector.

Go to step 3.

3

CHECK HARNESS BETWEEN ECM AND 
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between 
mass air flow and intake air temperature sensor 
connector and engine ground.

Connector & terminal

(B3) No. 4 — Engine ground:

Is the resistance less than 5 

:? Go to step 4.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and the mass
air flow and intake
air temperature
sensor connector.
• Poor contact in
ECM connector

4

CHECK POOR CONTACT.
Check for any poor contact in the mass air flow 
and intake air temperature sensor connector.

Is there poor contact in the 
mass air flow and intake air 
temperature sensor connector?

Repair any poor 
contact of the 
mass air flow and 
intake air tempera-
ture sensor con-
nector.

Replace the mass 
air flow and intake 
air temperature 
sensor. <Ref. to 
FU(H4SO)-28,
Mass Air Flow and 
Intake Air Temper-
ature Sensor.>

EN(H4SO)(diag)-117

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

P: DTC P0107 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE 

CIRCUIT LOW INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-30, DTC P0107 MANIFOLD ABSOLUTE PRESSURE/
BAROMETRIC PRESSURE CIRCUIT LOW INPUT, 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-04029

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

33 34

29

32

30 31

19

20

7

B21

E2

2

3

1

E21

E21

ECM

B21

B134

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

B134

MANIFOLD

ABSOLUTE
PRESSURE

SENSOR

1 2 3

29

6

19

EN(H4SO)(diag)-118

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake manifold absolute 
pressure signal using Subaru Select Monitor or 
general scan tool.

NOTE:
• SUBARU SELECT MONITOR
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO)(diag)-33, Subaru Select Moni-
tor.>
• General Scan Tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the measured value less than 
13.3 kPa (100 mmHg, 3.94 inHg)?

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
may be the cause.

2

CHECK POWER SUPPLY OF MANIFOLD 
ABSOLUTE PRESSURE SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from manifold 
absolute pressure sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between manifold 
absolute pressure sensor connector and 
engine ground.

Connector & terminal

(E21) No. 3 (+) — Engine 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 of
harness between
ECM and manifold
absolute pressure
sensor connector.
• Poor contact in
ECM connector
• Poor contact of
coupling connector

3

CHECK HARNESS BETWEEN ECM AND 
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance of harness between 
ECM and manifold absolute pressure sensor 
connector.

Connector & terminal

(B134) No. 6 — (E21) No. 1:

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 of
harness between
ECM and manifold
absolute pressure
sensor connector.
• Poor contact of
coupling connector

4

CHECK HARNESS BETWEEN ECM AND 
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
Measure the resistance between ECM and 
chassis ground.

Connector & terminal

(B134) No. 6 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 5.

Repair ground 
short circuit of har-
ness between 
ECM and manifold 
absolute pressure 
sensor connector.

5

CHECK POOR CONTACT.
Check for poor contact in ECM and manifold 
absolute pressure sensor connector.

Is there poor contact in ECM or 
manifold absolute pressure 
sensor connector?

Repair the poor 
contact in ECM or 
manifold absolute 
pressure sensor 
connector.

Replace the mani-
fold absolute pres-
sure sensor. <Ref. 
to FU(H4SO)-27, 
Manifold Absolute 
Pressure Sensor.>

 

 

 

 

 

 

 

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