Subaru 2009 IMPREZA Service Manual page 1539

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
19 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM and rear oxygen sensor connector.
Connector & terminal
(B135) No. 4 — (T6) No. 3:
(B135) No. 30 — (T6) No. 4:
20 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(T6) No. 3 (+) — Chassis ground (–):
Check
Is the resistance less than 1 ? Go to step 20.
Is the voltage 0.2 — 0.5 V?
EN(H4DOTC)(diag)-318
Yes No
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and rear oxy-
gen sensor con-
nector
• Poor contact of
coupling connector
Replace the rear Repair the harness
oxygen sensor. and connector.
<Ref. to
NOTE:
FU(H4DOTC)-50,
In this case, repair
Rear Oxygen Sen-
the following item:
sor.>
• Open circuit in
harness between
ECM and rear oxy-
gen sensor con-
nector
• Poor contact of
ECM connector
• Poor contact of
coupling connector