Subaru Legacy (2005 year). Manual - part 219

EN(H4SO 2.5)(diag)-161

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

6

CHECK HARNESS BETWEEN EGR SOLE-
NOID VALVE AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from EGR sole-
noid valve and ECM.
3) Measure the resistance of harness 
between EGR solenoid valve and ECM con-
nector.

Connector & terminal

(B134) No. 8 — (E18) No. 6:
(B134) No. 10 — (E18) No. 1:
(B134) No. 9 — (E18) No. 4:
(B134) No. 11 — (E18) No. 3:

Is the resistance less than 1 
Ω?

Go to step 7.

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

7

CHECK HARNESS BETWEEN EGR SOLE-
NOID VALVE AND ECM CONNECTOR.
Measure the resistance of harness between 
EGR solenoid valve 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 resistance more than 1 
M

Ω?

Go to step 8.

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

8

CHECK POOR CONTACT.
Check poor contact in ECM and EGR solenoid 
valve connector.

Is there poor contact of ECM 
and EGR solenoid valve con-
nector?

Repair the poor 
contact of ECM 
and EGR solenoid 
valve connector.

Even if the mal-
function indicator 
light illuminates, 
the circuit has 
returned to the 
specified condi-
tion at this time.

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-162

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AK:DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD 

(BANK1)

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.
TROUBLE SYMPTOM:
• Engine stalls.
• Idle mixture is out of specifications.

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:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03458

B327

B19

3

4

5

6

1

2

1 2
3 4

BATTERY

B327

1

2

4

6

3

5

B2

D24

C35

D31

A6

A7

REAR 

OXYGEN SENSOR

ECM

1

3

4

2

52

B21

B19

E2

B135

B:

D: B137

SBF-5

C: B136

E

E

A: B134

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

B136

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

35

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:

C:

D:

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

1 2 3 4
5 6 7 8

B83

*

: TERMINAL No. RANDOM ARRANGEMENT

*

*

OXYGEN (A/F) 
SENSOR RELAY

B83

EN(H4SO 2.5)(diag)-163

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 ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

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

NOTE:
In this case, it is
not necessary to
inspect DTC
P0420.

Go to step 3.

3

CHECK HARNESS BETWEEN ECM AND 
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
rear oxygen sensor.
3) Measure the resistance of harness 
between ECM and rear oxygen sensor con-
nector.

Connector & terminal

(B137) No. 24 — (B19) No. 3:
(B136) No. 35 — (B19) No. 4:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair open circuit 
in harness 
between ECM and 
rear oxygen sen-
sor connector.

4

CHECK HARNESS BETWEEN ECM AND 
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance between rear oxygen 
sensor harness connector and chassis ground.

Connector & terminal

(B137) No. 31 — Chassis ground:

Is the resistance less than 1 
Ω?

Go to step 5.

Repair open circuit 
in harness 
between ECM and 
rear oxygen sen-
sor connector.

5

CHECK EXHAUST SYSTEM.
Check for gas leaks or air suction caused by 
loose or dislocated nuts and bolts, and open 
hole at exhaust pipes.

NOTE:

Check the following positions.
• Between cylinder head and front exhaust 
pipe
• Between front exhaust pipe and front cata-
lytic converter
• Between front catalytic converter and rear 
catalytic converter

Is there a fault in exhaust sys-
tem?

Repair or replace 
the exhaust sys-
tem. <Ref. to 
EX(H4SO 2.0)-2, 
General Descrip-
tion.>

Go to step 6.

6

CHECK CATALYTIC CONVERTER.

Is there damage at rear face or 
front face of front catalyst?

Replace the cata-
lytic converter. 
<Ref. to EC(H4SO 
2.0)-3, Front Cata-
lytic Converter.>

Contact the SUB-
ARU dealer.

EN(H4SO 2.5)(diag)-164

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AL:DTC P0458 EVAPORATIVE EMISSION SYSTEM PURGE CONTROL VALVE 

CIRCUIT LOW

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.
TROUBLE SYMPTOM:
Erroneous idling

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:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03465

PURGE CONTROL

SOLENOID VALVE

E4

B21

E2

B47

B47

3

4

1

2

5

6

SBF-7

BATTERY

MAIN RELAY

1

2

6

3

5

14

2

1

48

41

B134

ECM

E4

1 2

E

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

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

4