Subaru Legacy (2005 year). Manual - part 446

EN(H6DO)(diag)-97

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

M: DTC P0057 HO2S HEATER CONTROL CIRCUIT LOW (BANK 2 SENSOR 2)

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.

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

B3

D31

D25

D24

B2

C35

4

3

1

REAR 

OXYGEN

SENSOR LH

E25

2

4

3

1

REAR 

OXYGEN 

SENSOR RH

E61

E3

B22

14

13

15

E3

B22

10

11

12

9

B83

B47

3

4

5

6

1

2

EN-03495

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

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:

16

B134

A:

B135

B:

B136

C:

B137

D:

B22

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

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

C:

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

D:

1 2 3 4
5 6 7 8

B83

3 4

1 2

E25

E61

E

E

5
3

: TERMINAL No. 
   RANDOM ARRANGEMENT

*

*

*

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EN(H6DO)(diag)-98

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen 
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen 
sensor connector and chassis ground.

Connector & terminal

(E25) No. 2 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 2.

Repair the power 
supply line.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
main relay and 
rear oxygen sen-
sor connector
• Poor contact in 
rear oxygen sen-
sor connector
• Poor contact in 
coupling connector

2

CHECK GROUND CIRCUIT FOR ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness 
between ECM connector and chassis ground.

Connector & terminal

(B134) No. 4 — Chassis ground:
(B134) No. 5 — Chassis ground:
(B134) No. 6 — Chassis ground:
(B134) No. 7 — Chassis ground:

Is the resistance less than 5 
Ω?

Go to step 3.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
ECM and engine 
ground terminal
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector

3

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of rear oxygen sensor heater 
current 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(H6DO)(diag)-26, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedure, refer to the 
general scan tool operation manual.

Is the current more than 0.2 A? Repair the con-

nector.

NOTE:
In this case, repair
the following:
• Poor contact in 
rear oxygen sen-
sor connector
• Poor contact in 
coupling connector
• Poor contact in 
ECM connector

Go to step 4.

4

CHECK OUTPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.

Connector & terminal

(B135) No. 3 (+) — Chassis ground (

−

):

Is the voltage less than 1 V?

Go to step 7.

Go to step 5.

5

CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector 
and chassis ground.

Connector & terminal

(B135) No. 3 (+) — Chassis ground (

−

):

Does the voltage change by 
shaking the ECM harness and 
connector while monitoring the 
value of voltage meter?

Repair the poor 
contact in ECM 
connector.

Go to step 6.

EN(H6DO)(diag)-99

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

6

CHECK OUTPUT SIGNAL FROM ECM.
1) Disconnect the connector from rear oxygen 
sensor.
2) Measure the voltage between ECM con-
nector and chassis ground.

Connector & terminal

(B135) No. 3 (+) — Chassis ground (

−

):

Is the voltage less than 1 V?

Replace the ECM. 
<Ref. to 
FU(H6DO)-34, 
Engine Control 
Module (ECM).>

Repair the battery 
short circuit of har-
ness between 
ECM and rear oxy-
gen sensor con-
nector. After 
repair, replace the 
ECM. <Ref. to 
FU(H6DO)-34, 
Engine Control 
Module (ECM).>

7

CHECK REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between rear oxy-
gen sensor connector terminals.

Terminal

No. 1 — No. 2:

Is the resistance less than 30 
Ω?

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
rear oxygen sen-
sor and ECM con-
nector
• Poor contact in 
rear oxygen sen-
sor connector
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector

Replace the rear 
oxygen sensor. 
<Ref. to 
FU(H6DO)-32, 
Rear Oxygen Sen-
sor.>

Step

Check

Yes

No

EN(H6DO)(diag)-100

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

N: DTC P0058 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 2 SENSOR 2)

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.

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

B3

D31

D25

D24

B2

C35

4

3

1

REAR 

OXYGEN

SENSOR LH

E25

2

4

3

1

REAR 

OXYGEN 

SENSOR RH

E61

E3

B22

14

13

15

E3

B22

10

11

12

9

B83

B47

3

4

5

6

1

2

EN-03495

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

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:

16

B134

A:

B135

B:

B136

C:

B137

D:

B22

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

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

C:

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

D:

1 2 3 4
5 6 7 8

B83

3 4

1 2

E25

E61

E

E

5
3

: TERMINAL No. 
   RANDOM ARRANGEMENT

*

*

*

*