Subaru LEGACY 2006 Manual page 190

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
5 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 con-
nector.
Connector & terminal
(B135) No. 4 — (E23) No. 3:
(B134) No. 29 — (E23) No. 4:
6 CHECK HARNESS BETWEEN REAR OXY-
GEN SENSOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor harness connector and chassis ground.
Connector & terminal
(E23) No. 3 (+) — Chassis ground (–):
7 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
• Looseness and improper fitting of exhaust
system parts
• Damage (crack, hole etc.) of parts
• Looseness and improper fitting of parts be-
tween front oxygen (A/F) sensor and rear oxy-
gen sensor
Check
Is the resistance more than
3Ω?
Is the voltage 0.2 — 0.5 V?
Is there any fault in exhaust
system?
EN(H4SO)(diag)-153
ENGINE (DIAGNOSTICS)
Yes No
Repair the open Go to step 6.
circuit of harness
between ECM and
rear oxygen sen-
sor connector.
Replace the rear Repair the har-
oxygen sensor. ness and connec-
<Ref. to tor.
FU(H4SO)-34,
NOTE:
Rear Oxygen Sen-
In this case, repair
sor.>
the following item:
• Open circuit in
harness between
rear oxygen sen-
sor and ECM con-
nector
• Poor contact in
rear oxygen sen-
sor connector
• Poor contact in
ECM connector
Repair or replace Replace the rear
faulty parts. oxygen sensor.
<Ref. to
FU(H4SO)-34,
Rear Oxygen Sen-
sor.>