Subaru Legacy III (2000-2003 year). Manual — part 505

EN(H4DOSTC)-190

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AU:DTC P1134 — A/F SENSOR MICRO-COMPUTER PROBLEM —

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-00933

BATTERY

MAIN RELAY

SBF-5

B47

1

2

3

5

4

6

E

E

E3

3

8

9

4

5

19

29

18

ECM

B137

B22

2

4

1

3

B18

FRONT OXYGEN
(A/F) SENSOR

3 4

1 2

3

4

1

2

5

6

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

13 14 15 16

B22

B47

B18

B137

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

EN(H4DOSTC)-191

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Does the Subaru Select Monitor indicate DTC
P1134?

DTC P1134 indicated.

Replace the ECM.
<Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

It is not necessary
to inspect DTC
P1134.

EN(H4DOSTC)-192

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AV:DTC P1199 — DIFFERENTIAL PRESSURE SENSOR —

• TROUBLE SYMPTOM:

• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection
Mode.> .

EN-01006

B122

DIFFERENTIAL
PRESSURE
SENSOR

3

2

1

19

15

9

ECM

B135

B221

5
6

1 2 3

B221

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

B122

5 6

2

1

4

3

EN(H4DOSTC)-193

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK POWER SUPPLY TO DIFFEREN-
TIAL PRESSURE SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from differential

pressure sensor.

3) Turn the ignition switch to ON.
4) Measure the voltage between differential

pressure sensor and engine ground.

Connector & terminal

(B221) No. 1(+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.5 V

Go to step 2.

Repair or replace
the harness con-
nector between
ECM and differen-
tial pressure con-
nector.

2

CHECK HARNESS BETWEEN ECM AND
DIFFERENTIAL PRESSURE SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM and

differential pressure sensor.

Connector & terminal

(B221) No. 2 — (B135) No. 19:
(B221) No. 3 — (B135) No. 15:

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

1

Ω

Go to step 3.

Repair the open
circuit between
ECM and differen-
tial pressure sen-
sor.

3

CHECK HARNESS BETWEEN ECM AND
DIFFERENTIAL PRESSURE SENSOR.
Measure the resistance between differential
pressure sensor and engine ground.

Connector & terminal

(B221) No. 3 — engine ground:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 4.

Repair the ground
short circuit
between ECM and
differential pres-
sure sensor.

4

CHECK DIFFERENTIAL PRESSURE SEN-
SOR.
1) Turn the ignition switch to OFF.
2) Install the vacuum pump to secondary tur-

bocharger side hose fitting.

3) Apply 5 V to the terminals No.1 and No.2,

then connect terminal NO.3 to positive side
and terminal No.2 to negative side.

4) Measure the voltage between differential

pressure sensor terminals.

Terminal

No. 3 (+) — No. 2 (

−−−−

):

Does the voltage change as in the specified
range?

3.5 V at 66.7 kPa (500 mmHg,
19.69 inHg)
2.0 V at 0 kPa (0 mmHg, 0
inHg)
0.5 V at -66.7 kPa (-500
mmHg, (-19.69 inHg)

Go to step 5.

Replace the differ-
ential pressure
sensor.

5

CHECK POOR CONTACT.
Check poor contact in ECM and differential
pressure sensor connectors.
Is there poor contact in ECM and differential
pressure sensor connectors.

There is poor contact.

Repair the poor
contact in ECM
and differential
pressure sensor
connectors.

Replace the ECM.