Subaru Legacy (2005 year). Manual - part 205

EN(H4SO 2.5)(diag)-105

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

5

CHECK HARNESS BETWEEN MASS AIR 
FLOW AND INTAKE AIR TEMPERATURE 
SENSOR AND ECM CONNECTOR.
Measure the voltage between mass air flow 
and intake air temperature sensor connector 
and engine ground.

Connector & terminal

(B3) No. 4 (+) — Engine ground (

−

):

Is the voltage more than 3 V?

Go to step 6.

Repair the har-
ness and connec-
tor.

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

6

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

Connector & terminal

(B3) No. 5 — Engine ground:

Is the resistance less than 5 
Ω?

Replace the mass 
air flow and intake 
air temperature 
sensor. <Ref. to 
FU(H4SO 2.5)-26, 
Mass Air Flow and 
Intake Air Temper-
ature Sensor.>

Repair the har-
ness and connec-
tor.

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

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-106

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

L: DTC P0117 ENGINE COOLANT TEMPERATURE CIRCUIT LOW

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Hard to start
• Erroneous idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03461

35

14

19

8

B136

ECM

1

2

E2

B21

E8

ENGINE

COOLANT

TEMPERATURE

SENSOR

E8

B21

1 2 3 4
5 6 7 8

B83

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

B136

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

35

*

: TERMINAL No. RANDOM ARRANGEMENT

B83

1 2

*

*

EN(H4SO 2.5)(diag)-107

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK OPTION CODE.

Is the option code EC, EK, EH, 
ER or K4?

Go to step 2.

Refer to EN(H4SO 
2.0) section. <Ref. 
to EN(H4SO 
2.0)(diag)-64, List 
of Diagnostic Trou-
ble Code (DTC).>

NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.

2

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture 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 2.5)(diag)-25, Subaru Select 
Monitor.>
• General scan tool
For detailed operation procedure, refer to the 
general scan tool operation manual.

Is the engine coolant tempera-
ture more than 150

°C (302°F)?

Go to step 3.

Repair the poor 
contact.

NOTE:
In this case, repair
the following:
• Poor contact in 
engine coolant 
temperature sen-
sor
• Poor contact in 
ECM
• Poor contact in 
coupling connector
• Poor contact in 
joint connector

3

CHECK HARNESS BETWEEN ENGINE 
COOLANT TEMPERATURE SENSOR AND 
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from engine cool-
ant temperature sensor.
3) Turn the ignition switch to ON.
4) Read the data of engine coolant tempera-
ture 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 2.5)(diag)-25, Subaru Select 
Monitor.>
• General scan tool
For detailed operation procedure, refer to the 
general scan tool operation manual.

Is the engine coolant tempera-
ture less than 

−40°C (−40°F)?

Replace the 
engine coolant 
temperature sen-
sor. <Ref. to 
FU(H4SO 2.5)-20, 
Engine Coolant 
Temperature Sen-
sor.>

Repair the ground 
short circuit of har-
ness between 
engine coolant 
temperature sen-
sor and ECM con-
nector.

EN(H4SO 2.5)(diag)-108

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

M: DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Hard to start
• Erroneous idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK, EH, ER and K4 model

EN-03461

35

14

19

8

B136

ECM

1

2

E2

B21

E8

ENGINE

COOLANT

TEMPERATURE

SENSOR

E8

B21

1 2 3 4
5 6 7 8

B83

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

B136

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

35

*

: TERMINAL No. RANDOM ARRANGEMENT

B83

1 2

*

*