Subaru IMPREZA GD 2007 Series Manual page 252

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 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 — (E119) No. 3:
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(E119) No. 3 — Chassis ground:
3 CHECK REAR OXYGEN SENSOR.
Measure the resistance between rear oxygen
sensor terminals.
Terminals
No. 3 — No. 4
Check
Is the resistance less than 1 Ω? Go to step 2.
Is the resistance 1 MΩ or
more?
Is the resistance less than 1 Ω? Replace the rear
EN(H4SO)(diag)-143
ENGINE (DIAGNOSTICS)
Yes No
Repair the open
circuit of harness
between ECM and
rear oxygen sensor
connector.
Go to step 3. Repair short cir-
cuit of the harness
to ground between
ECM and rear oxy-
gen sensor con-
nector.
Even if the malfunc-
oxygen sensor. tion indicator light
<Ref. to illuminates, the cir-
FU(H4SO)-37, cuit has returned to
Rear Oxygen Sen- a normal condition
sor.> at this time. Repro-
duce the fault con-
dition, and
reperform the
check.
NOTE:
In this case, there
may be a tempo-
rary connector
contact failure.