Subaru Legacy (2005 year). Manual - part 218

EN(H4SO 2.5)(diag)-157

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK OPTION CODE.

Is the option code EC, EK, EH, 
ER or K4?

Go to step 2.

Refer to EN(H4SO 
2.0) section. <Ref. 
to EN(H4SO 
2.0)(diag)-64, List 
of Diagnostic Trou-
ble Code (DTC).>

NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.

2

CHECK HARNESS BETWEEN CAMSHAFT 
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft 
position sensor.
3) Measure the resistance of harness 
between camshaft position sensor connector 
and engine ground.

Connector & terminal

(E15) No. 1 — Engine ground:

Is the resistance more than 
100 k

Ω?

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
camshaft position 
sensor and ECM 
connector
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector

Go to step 3.

3

CHECK HARNESS BETWEEN CAMSHAFT 
POSITION SENSOR AND ECM CONNEC-
TOR.
Measure the resistance of harness between 
camshaft position sensor connector and 
engine ground.

Connector & terminal

(E15) No. 1 — Engine ground:

Is the resistance less than 10 
Ω?

Repair the ground 
short circuit of har-
ness between 
camshaft position 
sensor and ECM 
connector.

NOTE:
The harness be-
tween both con-
nectors are
shielded. Repair
the ground short
circuit of harness
with shield.

Go to step 4.

4

CHECK HARNESS BETWEEN CAMSHAFT 
POSITION SENSOR AND ECM CONNEC-
TOR.
Measure the resistance of harness between 
camshaft position sensor connector and 
engine ground.

Connector & terminal

(E15) No. 2 — Engine ground:

Is the resistance less than 5 
Ω?

Go to step 5.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
camshaft position 
sensor and ECM 
connector
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector

5

CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.

Is the camshaft position sensor 
installation bolt tightened 
securely?

Go to step 6.

Tighten the cam-
shaft position sen-
sor installation bolt 
securely.

EN(H4SO 2.5)(diag)-158

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

6

CHECK CAMSHAFT POSITION SENSOR.
1) Remove the camshaft position sensor.
2) Measure the resistance between connector 
terminals of camshaft position sensor.

Terminals

No. 1 — No. 2:

Is the resistance 1 — 4 k

Ω?

Repair the poor 
contact in cam-
shaft position sen-
sor connector.

Replace the cam-
shaft position sen-
sor. <Ref. to 
FU(H4SO 2.5)-22, 
Camshaft Position 
Sensor.>

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-159

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AJ:DTC P0400 EXHAUST GAS RECIRCULATION FLOW

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.
TROUBLE SYMPTOM:
• Movement performance problem when engine is low speed.
• Erroneous idling
• Movement performance problem

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.
WIRING DIAGRAM:

EN-03464

E

E

B47

E18

2

5

1

4

3

6

B21

E2

B21

E2

B21

E2

5
3

6

2
1

48

26

A10

A9

A11

A8

D2

D1

B4

25

29

30

35

36

SBF-7

BATTERY

MAIN RELAY

EGR

VALVE

A: B134

B: B135

D: B137

ECM

B47

E18

3

4

1

2

5

6

1

3

4 5 6

2

B1

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B134

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

33 34

29

32

30 31

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

29 30 31

32 33

34 35

A:

B:

D:

4

EN(H4SO 2.5)(diag)-160

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Check DTC using 
“List of Diagnostic 
Trouble Code 
(DTC)”. <Ref. to 
EN(H4SO 
2.5)(diag)-69, List 
of Diagnostic Trou-
ble Code (DTC).>

Go to step 2.

2

CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake manifold absolute 
pressure signal using Subaru Select Monitor or 
general scan tool.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to 
“READ CURRENT DATA FOR ENGINE”. <Ref. 
to EN(H4SO 2.5)(diag)-25, Subaru Select 
Monitor.>
• General scan tool
For detailed operation procedure, refer to the 
general scan tool operation manual.

Is the measured value more 
than 53.3 kPa (400 mmHg, 
15.75 inHg)?

Make sure that the 
EGR valve, mani-
fold absolute pres-
sure sensor and 
throttle body are 
installed securely.

Go to step 3.

3

CHECK POWER SUPPLY OF EGR SOLE-
NOID VALVE.
1) Disconnect the connector from EGR sole-
noid valve.
2) Turn the ignition switch to ON.
3) Measure the voltage between EGR sole-
noid valve and engine ground.

Connector & terminal

(E18) No. 2 (+) — Engine ground (

−

):

(E18) No. 5 (+) — Engine ground (

−

):

Is the voltage more than 10 V? Go to step 4.

Repair the open 
circuit of harness 
between main 
relay and EGR 
solenoid valve 
connector.

4

CHECK EGR SOLENOID VALVE.
Measure the resistance between EGR sole-
noid valve terminals.

NOTE:

Make sure there is no foreign material between
EGR solenoid valve and valve seat.

Terminals

No. 1 — No. 2:
No. 3 — No. 2:
No. 4 — No. 5:
No. 6 — No. 5:

Is the resistance 20 — 30 

Ω?

Go to step 5.

Replace the EGR 
solenoid valve. 
<Ref. to FU(H4SO 
2.5)-31, EGR 
Valve.>

5

CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the connector to ECM and EGR 
solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (

−

):

(B134) No. 9 (+) — Chassis ground (

−

):

(B134) No. 10 (+) — Chassis ground (

−

):

(B134) No. 11 (+) — Chassis ground (

−

):

Is the voltage 0 — 10 V?

Repair the poor 
contact portion in 
ECM connector.

Go to step 6.