Subaru Legacy IV (2008 year). Manual — part 322

EN(H4DOTC)(diag)-109

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

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

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-29, DTC P0103 MASS OR VOLUME AIR FLOW CIR-
CUIT 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(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05087

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

B3

E

B83

1

B3

ECM

B135

SBF-7

1 2 3 4 5

3

4

1

2

5

6

B47

*

*

2

4

3

5

34

18

26

30

35

B47

1

2

4

6

3

5

1 2 3 4
5 6 7 8

B83

BATTERY

MASS AIR FLOW &

INTAKE AIR

TEMPERATURE

SENSOR

MAIN RELAY

: TERMINAL No. OPTIONAL
ARRANGEMENT

*

EN(H4DOTC)(diag)-110

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(H4DOTC)(diag)-34, 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(H4DOTC)(diag)-34, 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. 2 — 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:
• pen 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(H4DOTC)-36,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

EN(H4DOTC)(diag)-111

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

N: DTC P0107 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE

CIRCUIT LOW INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-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(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05671

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

23

28

6

B21

E2

2

3

1

E21

E21

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

1 2 3

6

29

19

MANIFOLD

ABSOLUTE
PRESSURE

SENSOR

ECM

EN(H4DOTC)(diag)-112

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(H4DOTC)(diag)-34, 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. 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 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(H4DOTC)-
37, Manifold Abso-
lute Pressure Sen-
sor.>