Subaru Legacy 2003 Service Manual page 1913

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
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 connector and engine ground or
chassis ground.
Connector & terminal
(T6) No. 2 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
7 CHECK REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between rear oxy-
gen sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the measured value less than the speci-
fied value?
Step
EN(H4DOSTC)-74
Value
10 V
30 Ω
Yes
Go to step 7. Repair the power
supply line.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
main relay and
rear oxygen sen-
sor connector
• Poor contact in
rear oxygen sen-
sor connector
• Poor contact in
coupling connector
Repair the har- Replace the rear
ness and connec- oxygen sensor.
tor. <Ref. to
FU(H4DOSTC)-
NOTE:
39, Rear Oxygen
In this case, repair
Sensor.>
the following:
• 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
• Poor contact in
coupling connector
No