Subaru Legacy 2003 Service Manual page 497

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from rear oxygen
sensor.
3) Turn ignition switch to ON.
4) Measure voltage between rear oxygen sen-
sor connector and engine ground or chas-
sis ground.
Connector & terminal
(T6) No. 2 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
7 CHECK REAR OXYGEN SENSOR.
1) Turn ignition switch to OFF.
2) Measure resistance between rear oxygen
sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the measured value less than the speci-
fied value?
Step
EN(H4SO)-100
Value
10 V
30 Ω
Yes
Go to step 7. Repair power sup-
ply 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 harness Replace rear oxy-
and connector. gen sensor. <Ref.
to FU(H4SO)-43,
NOTE:
Rear Oxygen Sen-
In this case, repair
sor.>
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