Subaru Legacy 2004 Service Manual page 575

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
(B136) No. 23 — Chassis ground:
2 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:
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.
Check
Is the resistance more than
700 k&?
Is the resistance more than
700 k&?
Is the knock sensor installation
bolt tightened securely?
EN(H4SO 2.0)(diag)-143
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
Replace the knock Tighten the knock
sensor. <Ref. to sensor installation
FU(H4SO 2.0)-23, bolt securely.
Knock Sensor.>
No