Subaru Legacy III (2000-2003 year). Manual - part 124

EN(H4SO)-108

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

7

CHECK HARNESS BETWEEN ECM AND 
PRESSURE SENSOR CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from pressure sen-

sor.

3) Turn ignition switch to ON.
4) Measure voltage between intake air tem-

perature sensor and pressure sensor con-
nector and engine ground.

Connector & terminal

(E21) No. 3 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.5 V

Go to step 8.

Repair open circuit 
in harness 
between ECM and 
pressure sensor 
connector.

8

CHECK HARNESS BETWEEN ECM AND 
PRESSURE SENSOR CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between 

ECM and pressure sensor connector.

Connector & terminal

(B135) No. 19 — (E21) No. 1:

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

1 

Ω

Go to step 9.

Repair open circuit 
in harness 
between ECM and 
pressure sensor 
connector.

9

CHECK HARNESS BETWEEN ECM AND 
PRESSURE SENSOR CONNECTOR.
Measure resistance of harness between pres-
sure sensor connector and engine ground.

Connector & terminal

(E21) No. 2 — Engine ground:

Does the measured value exceed the specified 
value?

500 k

Ω

Go to step 10.

Repair ground 
short circuit in har-
ness between 
ECM and intake 
air temperature 
and pressure sen-
sor connector.

10

CHECK POOR CONTACT.
Check poor contact in intake manifold pressure 
sensor connector. 
Is there poor contact in intake manifold pres-
sure sensor connector?

There is poor contact.

Repair poor con-
tact in pressure 
sensor connector.

Replace pressure 
sensor.  <Ref. to 
FU(H4SO)-32, 
Pressure Sensor.>

Step

Value

Yes

No

EN(H4SO)-109

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H4SO)-110

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

H: DTC P0108 — MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRES-

SURE CIRCUIT HIGH INPUT —

• 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-01123

19

3

15

PRESSURE

SENSOR

B135

B135

B83

9

15

12

B21

E2

1

2

3

E21

B21

ECM

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

B83

1 2 3 4 5 6

E21

1 2 3

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

3

1

FG

2

4

EG

: FOR G.C.C COUNTRIES MODEL 

: EXCEPT FOR G.C.C COUNTRIES MODEL 

FG

EG

EN(H4SO)-111

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK CURRENT DATA.
1) Start engine.
2) Read the data of intake manifold absolute 

pressure signal using Subaru Select Moni-
tor or OBD-II general scan tool.
Does the measured value exceed the spec-
ified value?

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.

119.5 kPa (896.5 mmHg, 
35.29 inHg)

Go to step 9.

Go to step 2.

2

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM connector and 
chassis ground.

Connector & terminal

(B135) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified 
value?

4.5 V

Go to step 4.

Go to step 3.

3

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM connector and 
chassis ground.

Connector & terminal

(B135) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified 
value by shaking harness and connector of 
ECM while monitoring the value with voltage 
meter?

4.5 V

Repair poor con-
tact in ECM con-
nector.

Contact SUBARU 
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

4

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM connector and 
chassis ground.

Connector & terminal

(B135) No. 15 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

0.2 V

Go to step 6.

Go to step 5.

5

CHECK INPUT SIGNAL FOR ECM. (USING 
SUBARU SELECT MONITOR.)
Read data of atmospheric absolute pressure 
signal using Subaru Select Monitor.
Does the measured value exceed the specified 
value by shaking harness and connector of 
ECM while monitoring the value with Subaru 
Select Monitor?

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.>  

13.3 kPa (100 mmHg, 3.94 
inHg)

Repair poor con-
tact in ECM con-
nector.

Go to step 6.