Subaru Legacy III (2000-2003 year). Manual - part 134

EN(H4SO)-148

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

V: DTC P0133 — O2 SENSOR CIRCUIT SLOW RESPONSE (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)-149

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?

DTC indicated.

Inspect the rele-
vant DTC using 
“List of Diagnostic 
Trouble Code 
(DTC)”. <Ref. to 
EN(H4SO)-83, List 
of Diagnostic 
Trouble Code 
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0133.

Go to step 2.

2

CHECK EXHAUST SYSTEM.
Is there a problem in 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

There is a problem.

Repair exhaust 
system.

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

EN(H4SO)-150

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

W:  DTC P0134 — O2 SENSOR CIRCUIT NO ACTIVITY DETECTED (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)-151

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 — (E18) No. 1:
(B136) No. 22 — (B18) No. 2:

Is the measured value less than the speci-
fied value?

1 

Ω

Go to step 2.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ECM and fornt 
oxygen (A/F) sen-
sor connector
• Poor contact in 
front oxygen (A/F) 
sensor connector
• Poor contact in 
ECM connector

2

CHECK POOR CONTACT.
Chack poor contact in front oxygen (A/F) sen-
sor connector.
Is there poor contact in front oxygen (A/F) sen-
sor connector?

There is poor contact.

Repair poor con-
tact in front oxygen 
(A/F) sensor con-
nector.

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