Subaru Legacy (2005 year). Manual - part 468

EN(H6DO)(diag)-185

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

25

GROUP OF #5 AND #6 CYLINDERS

Are there any faults in #5 and 
#6 cylinders?

Repair or replace 
faulty parts.

NOTE:
• Check the fol-
lowing items.

• Spark plug
• Fuel injector
• Ignition coil
• Compres-
sion ratio

• If no abnormal is 
found, check for 
“IGNITION CON-
TROL SYSTEM” 
of #5 and #6 cylin-
ders side. <Ref. to 
EN(H6DO)(diag)-
60, IGNITION 
CONTROL SYS-
TEM, Diagnostics 
for Engine Start-
ing Failure.>

Inspect DTC 
P0171, P0172, 
P0174 or P0175 
using “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H6DO)(diag)-
66, List of Diag-
nostic Trouble 
Code (DTC).>

26

GROUP OF #1, #3 AND #5 CYLINDERS.

Are there any fault in #1, #3 
and #5 cylinders?

Repair or replace 
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plug
• Fuel injector
• Skipping timing 
chain teeth

Inspect DTC 
P0171, P0172, 
P0174 or P0175 
using “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H6DO)(diag)-
66, List of Diag-
nostic Trouble 
Code (DTC).>

27

GROUP OF #2, #4 AND #6 CYLINDERS.

Are there any fault in #2, #4 
and #6 cylinders?

Repair or replace 
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plug
• Fuel injector
• Compression 
ratio
• Skipping timing 
chain teeth

Inspect DTC 
P0171, P0172, 
P0174 or P0175 
using “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H6DO)(diag)-
66, List of Diag-
nostic Trouble 
Code (DTC).>

28

CYLINDER AT RANDOM

Is the engine idle rough?

Inspect DTC 
P0171, P0172, 
P0174 or P0175 
using “List of Diag-
nostic Trouble 
Code (DTC)”. 
<Ref. to 
EN(H6DO)(diag)-
66, List of Diag-
nostic Trouble 
Code (DTC).>

Repair or replace 
faulty parts.

NOTE:
Check the follow-
ing items.
• Spark plug
• Fuel injector
• Compression 
ratio

Step

Check

Yes

No

EN(H6DO)(diag)-186

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BF:DTC P0327 KNOCK SENSOR 1 CIRCUIT LOW (BANK 1 OR SINGLE SEN-

SOR)

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Poor driving performance
• Knocking occurs.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE, 
Inspection Mode.>.
WIRING DIAGRAM:

25

33

KNOCK

SENSOR

1(RH)

13

2

ECM

B136

B20

E1

E14

E14

1 2

24

KNOCK

SENSOR

2(LH)

14

2

E48

E48

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

B20

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

E

EN-02506

EN(H6DO)(diag)-187

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM har-
ness connector and chassis ground.

Connector & terminal

(B136) No. 25 — Chassis ground:

Is the resistance more than 
700 k

Ω?

Go to step 2.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
knock sensor and 
ECM connector
• Poor contact in 
knock sensor con-
nector
• Poor contact in 
coupling connector

2

CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock 
sensor connector terminal and engine ground.

Terminal

No. 2 — Engine ground:

Is the resistance more than 
700 k

Ω?

Go to step 3.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Poor contact in 
knock sensor con-
nector

3

CHECK CONDITION OF KNOCK SENSOR 
INSTALLATION.

Is the knock sensor installation 
bolt tightened securely?

Replace the knock 
sensor. <Ref. to 
FU(H6DO)-21, 
Knock Sensor.>

Tighten the knock 
sensor installation 
bolt securely.

EN(H6DO)(diag)-188

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BG:DTC P0328 KNOCK SENSOR 1 CIRCUIT HIGH (BANK 1 OR SINGLE SEN-

SOR)

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Poor driving performance
• Knocking occurs.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE, 
Inspection Mode.>.
WIRING DIAGRAM:

25

33

KNOCK

SENSOR

1(RH)

13

2

ECM

B136

B20

E1

E14

E14

1 2

24

KNOCK

SENSOR

2(LH)

14

2

E48

E48

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

B20

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

E

EN-02506