Subaru Legacy III (2000-2003 year). Service manual — part 133

EN(H4SO)-144

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

T: 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(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-01144

F44

B61

6

RHD

RHD

BATTERY

SBF-5

B47

MAIN RELAY

1

2

3

5

4

6

F44

1 2 3 4
5 6 7 8

C16

C5

4

8

B22

E3

ECM

C6

C17

C22

C13

B23

3

2

1

FRONT OXYGEN

(A/F) SENSOR

B18

B135

B:

B136

C:

B22

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

13 14 15 16

B47

3

4

5

6

1

2

B136

5 6

7

2

1

9

8

4

3

23

21 22

24

10 11 12 13 14

25 26

15 16 17

18 19 20

B18

4

2 1

3

LHD

LHD

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

B135

EN(H4SO)-145

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and front

oxygen (A/F) sensor connector.

3) Measure resistance of harness between

ECM and front oxygen (A/F) sensor con-
nector.

Connector & terminal

(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Replace front oxy-
gen (A/F) sensor.
<Ref. to
FU(H4SO)-41,
Front Oxygen (A/
F) Sensor.>

Repair short circuit
between ECM and
front oxygen (A/F)
sensor connector.

EN(H4SO)-146

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

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

—

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-01144

F44

B61

6

RHD

RHD

BATTERY

SBF-5

B47

MAIN RELAY

1

2

3

5

4

6

F44

1 2 3 4
5 6 7 8

C16

C5

4

8

B22

E3

ECM

C6

C17

C22

C13

B23

3

2

1

FRONT OXYGEN

(A/F) SENSOR

B18

B135

B:

B136

C:

B22

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

13 14 15 16

B47

3

4

5

6

1

2

B136

5 6

7

2

1

9

8

4

3

23

21 22

24

10 11 12 13 14

25 26

15 16 17

18 19 20

B18

4

2 1

3

LHD

LHD

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

B135

EN(H4SO)-147

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure voltage of harness between ECM

connector and chassis ground.

Connector & terminal

(B136) No. 13 (+) — Chassis ground (-):
(B136) No. 22 (+) — Chassis ground (-):

Does the measured value exceed the spec-
ified value?

8 V

Replace front oxy-
gen (A/F) sensor.
<Ref. to
FU(H4SO)-43,
Rear Oxygen Sen-
sor.>

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