Subaru Legacy IV (2008 year). Manual — part 324

EN(H4DOTC)(diag)-117

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Q: DTC P0112 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT LOW

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-34, DTC P0112 INTAKE AIR TEMPERATURE SEN-
SOR 1 CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• 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)-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 air temperature sen-
sor signal using Subaru Select Monitor or gen-
eral 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 intake air temperature
120°C (248°F) or higher?

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 ECM and
mass air flow and intake air temperature sensor.
3) Measure the resistance between ECM and
chassis ground.

Connector & terminal

(B135) No. 18 — Chassis ground:

Is the resistance 1 M

: or

more?

Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4DOTC)-36,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

Repair the ground
short circuit of har-
ness between the
ECM and the mass
air flow and intake
air temperature
sensor connectors.

EN(H4DOTC)(diag)-119

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

R: DTC P0113 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT HIGH

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-35, DTC P0113 INTAKE AIR TEMPERATURE SEN-
SOR 1 CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• 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)-120

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 air temperature sen-
sor signal using Subaru Select Monitor or gen-
eral 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 intake air temperature
less than –40°C (–40°F) ?

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 POOR CONTACT.
Check for poor contact in the ECM or the mass
air flow and intake air temperature sensor con-
nector.

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

Repair any poor
contact in the ECM
or the mass air flow
and intake air tem-
perature sensor
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) Disconnect the connector from ECM and
mass air flow and intake air temperature sensor.
3) Measure the resistance of harness between
ECM and mass air flow and intake air tempera-
ture sensor connectors.

Connector & terminal

(B135) No. 18 — (B3) No. 4:
(B135) No. 30 — (B3) No. 5:

Is the resistance less than 1

:? Go to step 4.

Repair the open
circuit of harness
between ECM and
mass air flow and
intake air tempera-
ture sensor con-
nector.

4

CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to OFF.
3) Measure the voltage between ECM and
chassis ground.

Connector & terminal

(B135) No. 18 (+) — Chassis ground (–):

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.

Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4DOTC)-36,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>