Subaru LEGACY 2006 Manual page 236

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
8 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(E23) No. 3 (+) — Chassis ground (–):
9 CHECK REAR OXYGEN SENSOR VOLT-
AGE.
1) Warm-up the engine until engine coolant
temperature is above 70°C (158°F), and rap-
idly reduce the engine speed from 3,000 rpm.
2) Read the voltage of rear oxygen sensor
using Subaru Select Monitor.
NOTE:
• For MT model, depress the clutch pedal.
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(diag)-26, Subaru Select Moni-
tor.>
10 CHECK CATALYTIC CONVERTER.
11 CHECK REAR OXYGEN SENSOR SHIELD.
1) Turn the ignition switch to OFF.
2) Bare the harness sensor shield on the body
side of rear oxygen sensor connector.
3) Measure the resistance between sensor
shield and chassis ground.
Check
Is the voltage 0.2 — 0.5 V?
Is the voltage 250 mV or less? Contact your SOA
Is the catalytic converter dam-
aged?
Is resistance less than 1 Ω?
EN(H4SO)(diag)-199
ENGINE (DIAGNOSTICS)
Yes No
Go to step 11. Repair the har-
ness and connec-
tor.
NOTE:
Repair the follow-
ing.
• Open circuit in
harness between
rear oxygen sen-
sor and ECM con-
nector
• Poor contact in
rear oxygen sen-
sor and ECM con-
nector
• Poor contact in
ECM connector
Go to step 6.
Service Center.
NOTE:
The probable
cause is consid-
ered as the deteri-
oration of multiple
parts.
Replace the cata- Contact your SOA
lytic converter. Service Center.
<Ref. to
NOTE:
EC(H4SO)-3,
The probable
Front Catalytic
cause is consid-
Converter.>
ered as the deteri-
oration of multiple
parts.
Replace the rear Repair the open
oxygen sensor. circuit of rear oxy-
<Ref. to gen sensor har-
FU(H4SO)-34, ness.
Rear Oxygen Sen-
sor.>