Subaru Legacy III (2000-2003 year). Manual - part 482

EN(H4DOSTC)-98

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

K: DTC P0117 — ENGINE COOLANT TEMPERATURE CIRCUIT LOW INPUT —

• 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(H4DOSTC)-35, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00936

B122

B135 ECM

19

18

E8

      ENGINE
    COOLANT
TEMPERATURE
     SENSOR

2

1

6

1

17

18

E8

1 2

3

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

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

B122

1 2 3 4 5 6

B21

E2

B21

EN(H4DOSTC)-99

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 engine coolant tempera-

ture 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.>

120

°

C (248

°

F)

Go to step 2.

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

2

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.
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.>  

−

40

°

C (

−

40

°

F)

Replace the 
engine coolant 
temperature sen-
sor. <Ref. to 
FU(H4DOSTC)-
28, Engine Cool-
ant Temperature 
Sensor.>

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

EN(H4DOSTC)-100

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

L: DTC P0118 — ENGINE COOLANT TEMPERATURE CIRCUIT HIGH INPUT —

• 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(H4DOSTC)-35, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00936

B122

B135 ECM

19

18

E8

      ENGINE
    COOLANT
TEMPERATURE
     SENSOR

2

1

6

1

17

18

E8

1 2

3

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

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

B122

1 2 3 4 5 6

B21

E2

B21

EN(H4DOSTC)-101

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 engine coolant tempera-

ture 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.>

−

40

°

C (

−

40

°

F)

Go to step 2.

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

2

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) Measure the voltage between engine cool-

ant temperature sensor connector and 
engine ground.

Connector & terminal

(E8) No. 2 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Repair the battery 
short circuit in har-
ness between 
ECM and engine 
coolant tempera-
ture sensor con-
nector.

Go to step 3.

3

CHECK HARNESS BETWEEN ENGINE 
COOLANT TEMPERATURE SENSOR AND 
ECM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between engine cool-

ant temperature sensor connector and 
engine ground.

Connector & terminal

(E8) No. 2 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Repair the battery 
short circuit in har-
ness between 
ECM and engine 
coolant tempera-
ture sensor con-
nector.

Go to step 4.