Subaru Legacy IV (2008 year). Manual - part 355

EN(H4DOTC)(diag)-241

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CA:DTC P0506 IDLE AIR CONTROL SYSTEM RPM LOWER THAN EXPECTED

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-148, DTC P0506 IDLE AIR CONTROL SYSTEM RPM
LOWER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Hard to start the engine.
• Engine does not start.
• Improper idling
• Engine stalls.

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05673

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

1 2

7 8

3
4

5
6

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 3 4
5 6 7 8

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

1

2

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

7

32 33 34 35

1 2 3 4 5 6

E57

B47

B137

D:

B21

B122

B136

C:

B362

B134

A:

36

40

34

35

37

E2

B21

C21

C1

A29

6

A18

C6

A28

6

4

25

*

*

B122

24

E

38

39

28

D5

D4

A19

A5

D7

D1

D2

D3

3

E57

2

1

5

B134

B362

B47

5

7

6

A:

B137

B136

D:

C:

*

E

SBF-7

8

6

4

E

3

4

1

2

5

6

ELECTRONIC
THROTTLE 
CONTROL RELAY

MAIN RELAY

BATTERY

ECM

ELECTRONIC THROTTLE 
CONTROL

: TERMINAL No. OPTIONAL 
  ARRANGEMENT

EN(H4DOTC)(diag)-242

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appro-
priate DTC using 
the “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H4DOTC)(diag)
-81, List of Diag-
nostic Trouble 
Code (DTC).>

Go to step 2.

2

CHECK AIR CLEANER ELEMENT.
1) Turn the ignition switch to OFF.
2) Check the air cleaner element.

Is the air cleaner element 
excessively clogged?

Replace the air 
cleaner element. 
<Ref. to 
IN(H4DOTC)-7, Air 
Cleaner Element.>

Go to step 3.

3

CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Remove the electronic throttle control. <Ref. 
to FU(H4DOTC)-14, REMOVAL, Throttle 
Body.>
2) Check the electronic throttle control.

Are foreign matter found inside 
electronic throttle control?

Remove foreign 
matter from elec-
tronic throttle con-
trol.

Perform the diag-
nosis of DTC 
P2101. <Ref. to 
EN(H4DOTC)(diag)
-318, DTC P2101 
THROTTLE 
ACTUATOR CON-
TROL MOTOR 
CIRCUIT RANGE/
PERFORMANCE, 
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code 
(DTC).>

EN(H4DOTC)(diag)-243

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CB:DTC P0507 IDLE AIR CONTROL SYSTEM RPM HIGHER THAN EXPECTED

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-149, DTC P0507 IDLE AIR CONTROL SYSTEM RPM
HIGHER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine keeps running at higher speed than specified idle speed.

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05673

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

1 2

7 8

3
4

5
6

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 3 4
5 6 7 8

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

1

2

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

7

32 33 34 35

1 2 3 4 5 6

E57

B47

B137

D:

B21

B122

B136

C:

B362

B134

A:

36

40

34

35

37

E2

B21

C21

C1

A29

6

A18

C6

A28

6

4

25

*

*

B122

24

E

38

39

28

D5

D4

A19

A5

D7

D1

D2

D3

3

E57

2

1

5

B134

B362

B47

5

7

6

A:

B137

B136

D:

C:

*

E

SBF-7

8

6

4

E

3

4

1

2

5

6

ELECTRONIC
THROTTLE 
CONTROL RELAY

MAIN RELAY

BATTERY

ECM

ELECTRONIC THROTTLE 
CONTROL

: TERMINAL No. OPTIONAL 
  ARRANGEMENT

EN(H4DOTC)(diag)-244

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appro-
priate DTC using 
the “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H4DOTC)(diag)
-81, List of Diag-
nostic Trouble 
Code (DTC).>

Go to step 2.

2

CHECK AIR INTAKE SYSTEM.
1) Start and idle the engine.
2) Check the following items.
• Loose installation of intake manifold and 
throttle body
• Cracks of intake manifold gasket and throttle 
body gasket
• Disconnection of vacuum hoses

Is there any fault in air intake 
system?

Repair air suction 
and leaks.

Go to step 3.

3

CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control. <Ref. 
to FU(H4DOTC)-14, REMOVAL, Throttle 
Body.>
3) Check the electronic throttle control.

Are foreign matter found inside 
electronic throttle control?

Remove foreign 
matter from elec-
tronic throttle con-
trol.

Perform the diag-
nosis of DTC 
P2101. <Ref. to 
EN(H4DOTC)(diag)
-318, DTC P2101 
THROTTLE 
ACTUATOR CON-
TROL MOTOR 
CIRCUIT RANGE/
PERFORMANCE, 
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code 
(DTC).>