Subaru Legacy III (2000-2003 year). Manual - part 141

EN(H4SO)-176

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AG:DTC P0327 — KNOCK SENSOR 1 CIRCUIT LOW INPUT (BANK 1 OR SIN-

GLE SENSOR) —

• 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)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00728

16

27

KNOCK

SENSOR

16

2

ECM

B135

B21

E2

E14

B21

E14

1 2

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

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

B135

EN(H4SO)-177

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance between ECM harness 

connector and chassis ground.

Connector & terminal

(B135) No. 16 — Chassis ground:

Does the measured value exceed the spec-
ified value?

700 k

Ω

Go to step 2.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
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 connector from knock sensor.
2) Measure resistance between knock sensor 

connector terminal and engine ground.

Terminal

No. 2 — Engine ground:

Does the measured value exceed the spec-
ified value?

700 k

Ω

Go to step 3.

Repair harness 
and connector.

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

3

CHECK CONDITION OF KNOCK SENSOR 
INSTALLATION.
Is the knock sensor installation bolt tightened 
securely?

Tightened securely.

Replace knock 
sensor. <Ref. to 
FU(H4SO)-29, 
Knock Sensor.>

Tighten knock 
sensor installation 
bolt securely.

EN(H4SO)-178

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AH:DTC P0328 — KNOCK SENSOR 1 CIRCUIT HIGH INPUT (BANK 1 OR SIN-

GLE SENSOR) —

• 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)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-00728

16

27

KNOCK

SENSOR

16

2

ECM

B135

B21

E2

E14

B21

E14

1 2

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

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

B135

EN(H4SO)-179

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

Connector & terminal

(B135) No. 16 — Chassis ground:

Is the measured value less than the specified 
value?

400 k

Ω

Go to step 2.

Go to step 3.

2

CHECK KNOCK SENSOR.
1) Disconnect connector from knock sensor.
2) Measure resistance between knock sensor 

connector terminal and engine ground.

Terminal

No. 2 — Engine ground:

Is the measured value less than the speci-
fied value?

400 k

Ω

Replace knock 
sensor. <Ref. to 
FU(H4SO)-29, 
Knock Sensor.>

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

NOTE:
The harness be-
tween both con-
nectors is
shielded. Repair
short circuit of har-
ness together with
shield.

3

CHECK INPUT SIGNAL FOR ECM.
1) Connect connectors to ECM and knock 

sensor.

2) Turn ignition switch to ON.
3) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

(B135) No. 16 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

2 V

Even if MI lights 
up, the circuit has 
returned to a nor-
mal condition at 
this time. (How-
ever, the possibil-
ity 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 poor con-
tact in ECM con-
nector.