Subaru Legacy IV (2008 year). Manual - part 329

EN(H4DOTC)(diag)-137

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AB:DTC P0133 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-50, DTC P0133 O2 SENSOR CIRCUIT SLOW RE-
SPONSE (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

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-05669

SBF-5

B47

B21

E2

B21

E2

1

2

4

6

3

5

E

E

C2

C3

B8

B9

B1

B134

4

3

2

1

E79

3 4

1 2

3

4

1

2

5

6

B21

B47

E79

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:

B135

B:

B136

C:

B137

D:

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

A:

D2

A5

D3

E2

B21

E

35

34

40

D7

36

D1

37

B138

*

*

*

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

B136

C:

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

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B:

D:

1 2 3 4
5 6 7 8

B138

42

26

43

15

MAIN RELAY

BATTERY

FRONT 
OXYGEN (A/F)  
SENSOR

ECM

: TERMINAL No. OPTIONAL 
  ARRANGEMENT 
  AMONG 1, 2, 5  AND 6

EN(H4DOTC)(diag)-138

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK EXHAUST SYSTEM.

NOTE:
Check the following items.
• Loose installation of front portion of exhaust
pipe onto cylinder heads
• Loose connection between front exhaust pipe
and front catalytic converter
• Damage of exhaust pipe resulting in a hole

Is there any fault in exhaust 
system?

Repair the exhaust 
system.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4DOTC)-46, 
Front Oxygen (A/F) 
Sensor.>

EN(H4DOTC)(diag)-139

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AC:DTC P0134 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED 

(BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-53, DTC P0134 O2 SENSOR CIRCUIT NO ACTIVITY
DETECTED (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

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-05669

SBF-5

B47

B21

E2

B21

E2

1

2

4

6

3

5

E

E

C2

C3

B8

B9

B1

B134

4

3

2

1

E79

3 4

1 2

3

4

1

2

5

6

B21

B47

E79

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:

B135

B:

B136

C:

B137

D:

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

A:

D2

A5

D3

E2

B21

E

35

34

40

D7

36

D1

37

B138

*

*

*

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

B136

C:

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

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B:

D:

1 2 3 4
5 6 7 8

B138

42

26

43

15

MAIN RELAY

BATTERY

FRONT 
OXYGEN (A/F)  
SENSOR

ECM

: TERMINAL No. OPTIONAL 
  ARRANGEMENT 
  AMONG 1, 2, 5  AND 6

EN(H4DOTC)(diag)-140

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

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 connectors from ECM and 
front oxygen (A/F) sensor connector.
3) Measure the resistance of harness between 
ECM and front oxygen (A/F) sensor connector.

Connector & terminal

(B135) No. 9 — (E79) No. 1:
(B135) No. 8 — (E79) No. 3:

Is the resistance less than 1 

:? Go to step 2.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and front oxy-
gen (A/F) sensor
connector
• Poor contact of
coupling connector

2

CHECK POOR CONTACT.
Check for poor contact of ECM and front oxygen 
(A/F) sensor connector.

Is there poor contact in ECM or 
front oxygen (A/F) sensor con-
nector?

Repair the poor 
contact in ECM or 
front oxygen (A/F) 
sensor connector.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4DOTC)-46, 
Front Oxygen (A/F) 
Sensor.>