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.