Subaru Legacy (2005 year). Service manual — part 456

EN(H6DO)(diag)-137

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AD:DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP

FUEL CONTROL

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.
TROUBLE SYMPTOM:
Engine would not return to idling.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE,
Inspection Mode.>.

Step

Check

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)(diag)-
66, List of Diag-
nostic Trouble
Code (DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0125.

Go to step 2.

2

CHECK TIRE SIZE.

Is the tire specified size and
one same size as other three
wheels?

Go to step 3.

Replace the tire.

3

CHECK ENGINE COOLANT.
Check the following items:
• Amount of engine coolant
• Coolant freeze
• Contamination of engine coolant

Is the engine coolant normal?

Go to step 4.

Fill or replace the
engine coolant.
<Ref. to
CO(H6DO)-12,
INSPECTION,
Engine Coolant.>

4

CHECK THERMOSTAT.

Does the thermostat remain
opened?

Replace the ther-
mostat. <Ref. to
CO(H6DO)-14,
Thermostat.>

Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H6DO)-18,
Engine Coolant
Temperature Sen-
sor.>

EN(H6DO)(diag)-138

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AE:DTC P0131 O2 SENSOR CIRCUIT LOW VOLTAGE (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
Immediately at fault recognition

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

BATTERY

SBF-5

B47

MAIN RELAY

A4

A5

A6

A7

2

52

54

B21

E2

ECM

A34

A27

B7

A1

A2

A3

A26

A33

4

1

3

FRONT

OXYGEN

(A/F)

SENSOR LH

E24

2

B135

B:

B134

A:

4

3

1

FRONT

OXYGEN

(A/F)

SENSOR RH

E47

E3

B22

8

5

6

E3

B22

2

1

3

4

B47

3

4

5

6

1

2

A25

B22

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

3 4

1 2

E47

E24

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

B:

B134

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

A:

B21

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

E

E

EN-03494

B135

B:

B134

A:

7

5
3

EN(H6DO)(diag)-139

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor connector.
3) Measure the resistance of harness
between ECM and chassis ground.

Connector & terminal

(B134) No. 26 — Chassis ground:
(B134) No. 33 — Chassis ground:

Is the resistance more than 1
M

Ω?

Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H6DO)-30,
Front Oxygen (A/
F) Sensor.>

Repair the ground
short circuit of har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.

EN(H6DO)(diag)-140

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AF:DTC P0132 O2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
Immediately at fault recognition

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

BATTERY

SBF-5

B47

MAIN RELAY

A4

A5

A6

A7

2

52

54

B21

E2

ECM

A34

A27

B7

A1

A2

A3

A26

A33

4

1

3

FRONT

OXYGEN

(A/F)

SENSOR LH

E24

2

B135

B:

B134

A:

4

3

1

FRONT

OXYGEN

(A/F)

SENSOR RH

E47

E3

B22

8

5

6

E3

B22

2

1

3

4

B47

3

4

5

6

1

2

A25

B22

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

3 4

1 2

E47

E24

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

B:

B134

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

A:

B21

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

E

E

EN-03494

B135

B:

B134

A:

7

5
3