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.>