Subaru Impreza 2003 Service Manual page 1343

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
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
(B135) No. 4 — Chassis ground:
2 CHECK KNOCK SENSOR.
1)Disconnect the connector from knock sen-
sor.
2)Measure the resistance between knock sen-
sor connector terminal and engine ground.
Terminals
No. 2 — Engine ground:
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.
Check
Is the resistance more than
700 kΩ?
Is the resistance more than
700 kΩ?
Is the knock sensor installa-
tion bolt tightened securely?
EN(H4DOTC)-167
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the har-
ness and connec-
tor.
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
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
• Poor contact in
coupling connector
Replace the knock Tighten the knock
sensor. <Ref. to sensor installation
FU(H4DOTC)-32, bolt securely.
Knock Sensor.>
No