Subaru Legacy III (2000-2003 year). Manual - part 480

EN(H4DOSTC)-90

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

6

CHECK HARNESS BETWEEN ECM AND 
PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness 

between ECM and pressure sensor con-
nector.

Connector & terminal

(B135) No. 8 — (E21) No. 1:
(B135) No. 19 — (E21) No. 2:

Is the measured value less than the speci-
fied value?

1 

Ω

Go to step 7.

Repair the open 
circuit in harness 
between ECM and 
pressure sensor 
connector.

7

CHECK POOR CONTACT.
Check poor contact in pressure sensor con-
nector. 
Is there poor contact in pressure sensor con-
nector?

There is poor contact.

Repair the poor 
contact in pres-
sure sensor con-
nector.

Replace the pres-
sure sensor. <Ref. 
to FU(H4DOSTC)-
34, Pressure Sen-
sor.>

Step

Value

Yes

No

EN(H4DOSTC)-91

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H4DOSTC)-92

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

I:

DTC P0112 — INTAKE AIR TEMPERATURE CIRCUIT LOW INPUT —

• TROUBLE SYMPTOM:

• Erroneous idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00951

B122

B3

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

BATTERY

E

B122

1

B3

MASS  AIR  FLOW  AND 
INTAKE AIR TEMPERATURE

ECM

B135

B :

B84

E :

SBF-5

1 2 3 4 5

3

4

1

2

5

6

1 2 3 4 5 6

B84

B47

2
6

2

4

3

5

E7

B27

E13

B19

E8

1 2 3

8 9 10

4

11 12

13 14 15

16

5 6

7

17

MAIN  RELAY

B47

1

2

3

5

4

6

EN(H4DOSTC)-93

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake air temperature 

sensor signal using Subaru Select Monitor.
Does the measured value exceed the spec-
ified value?

NOTE:

For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>  

55

°

C (131

°

F)

Go to step 2.

Repair the poor 
contact.

NOTE:
In this case, repair
the following:
• Poor contact 
mass air flow and 
intake air tempera-
ture sensor
• Poor contact in 
ECM
• Poor contact in 
joint connector

2

CHECK HARNESS BETWEEN MASS AIR 
FLOW AND INTAKE AIR TEMPERATURE 
SENSOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air 

flow and intake air temperature sensor.

3) Turn the ignition switch to ON.
4) Read the data of intake air temperature 

sensor signal using Subaru Select Monitor.
Is the measured value less than the speci-
fied value?

NOTE:

For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>

−

36

°

C (

−

97

°

F)

Replace the mass 
air flow and intake 
air temperature 
sensor.  <Ref. to 
FU(H4DOSTC)-
33, Mass Air Flow 
and Intake Air 
Temperature Sen-
sor.>

Repair the ground 
short circuit in har-
ness between 
mass air flow and 
intake air tempera-
ture sensor and 
ECM connector.