Subaru Legacy (2005 year). Manual - part 216

EN(H4SO 2.5)(diag)-149

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AF: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(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-03462

25

33

KNOCK

SENSOR

13

2

ECM

B136

B20

E1

E14

E14

1 2

B20

E

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

1 2 3 4
5 6 7 8
9 10 11 12

14

13

15 16

EN(H4SO 2.5)(diag)-150

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 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 3.

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

3

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

Terminals

No. 2 — Engine ground:

Is the resistance more than 
700 k

Ω?

Go to step 4.

Repair the har-
ness and connec-
tor.

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

4

CHECK INSTALLATION CONDITION OF 
KNOCK SENSOR.

Is the knock sensor installation 
bolt tightened securely?

Replace the knock 
sensor. <Ref. to 
FU(H4SO 2.5)-23, 
Knock Sensor.>

Tighten the knock 
sensor installation 
bolt securely.

EN(H4SO 2.5)(diag)-151

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AG: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(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-03462

25

33

KNOCK

SENSOR

13

2

ECM

B136

B20

E1

E14

E14

1 2

B20

E

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

1 2 3 4
5 6 7 8
9 10 11 12

14

13

15 16

EN(H4SO 2.5)(diag)-152

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 KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure the resistance of harness between 
ECM connector and chassis ground.

Connector & terminal

(B136) No. 25 — Chassis ground:

Is the resistance less than 400 
k

Ω?

Go to step 3.

Go to step 4.

3

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

Terminals

No. 2 — Engine ground:

Is the resistance less than 400 
k

Ω?

Replace the knock 
sensor. <Ref. to 
FU(H4SO 2.5)-23, 
Knock Sensor.>

Repair the ground 
short circuit of har-
ness between 
knock sensor con-
nector and ECM 
connector.

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

4

CHECK INPUT SIGNAL OF ECM.
1) Connect the connectors to ECM and knock 
sensor.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 25 (+) — Chassis ground (

−

):

Is the voltage more than 2 V?

Even if the mal-
function indicator 
light illuminates, 
the circuit has 
returned to a nor-
mal condition at 
this time. (How-
ever, the possibility 
of poor contact still 
remains.)

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

Repair the poor 
contact in ECM 
connector.