Subaru Legacy III (2000-2003 year). Manual — part 166

EN(H4SO)-276

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BV: DTC P1137 — O2 SENSOR CIRCUIT (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)-277

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).>

Go to step 2.

2

CHECK FRONT OXYGEN (A/F) SENSOR DA-
TA.
1) Start engine.
2) While observing the Subaru Select Monitor

or OBD-II general scan tool screen, warm-
up the engine until coolant temperature is
above 70

°

C (158

°

F).

If the engine is already warmed-up, operate
at idle speed for at least 1 minute.

3) Read data of front oxygen (A/F) sensor sig-

nal using Subaru Select Monitor or OBD-II
general scan tool.
Is the measured value within the specified
range?

NOTE:

•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)-32, Subaru Select Moni-
tor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.

0.85 - 1.15

Go to step 3.

Go to step 4.

3

CHECK FRONT OXYGEN (A/F) SENSOR DA-
TA.
Race engine at speeds from idling to 5,000
rpm for a total of 5 cycles.
Does the measured value exceed the specified
value?

NOTE:

•Normally, A/F mixture ratio is rich with racing
engine.
•To increase engine speed to 5,000 rpm,
slowly depress accelerator pedal, taking
approximately 5 seconds, and quickly release
accelerator pedal to decrease engine speed.

1.1

Go to step 6.

Go to step 4.

4

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

oxygen (A/F) sensor connector.

3) Measure resistance between ECM and

front oxygen (A/F) sensor.

Connector & terminals

(B136) No. 13 — (B18) No. 1:
(B136) No. 22 — (B18) No. 2:

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

5

Ω

Go to step 5.

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

EN(H4SO)-278

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

5

CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure resistance between ECM and chas-
sis ground.

Connector & terminals

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

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 6.

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

6

CHECK EXHAUST SYSTEM.
Check exhaust system parts.
Is there any fault in exhaust system?

NOTE:

Check the following items.
•Loose installation of portions
•Damage (crack, hole etc.) of parts
•Looseness of front oxygen (A/F) sensor
•Looseness and ill fitting of parts between front
oxygen (A/F) sensor and rear oxygen sensor

There is a fault.

Repair or replace
faulty parts.

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

Step

Value

Yes

No

EN(H4SO)-279

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BW:DTC P1492 — EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION

(LOW INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)-280, DTC P1498 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

BX:DTC P1493 — EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)-282, DTC P1499 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

BY:DTC P1494 — EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION

(LOW INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)-280, DTC P1498 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

BZ:DTC P1495 — EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)-282, DTC P1499 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CA:DTC P1496 — EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION

(LOW INPUT)—

NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(H4SO)-280, DTC P1498 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

CB:DTC P1497 — EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(H4SO)-282, DTC P1499 — EGR SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>