Subaru IMPREZA 2004 Service Manual page 12

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
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 chas-
sis ground.
Connector & terminal
(B19) No. 2 (+) — Chassis ground ( − − − − ):
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:
Check
Is the voltage more than 10 V? Go to step 7.
Is the resistance less than 30
Ω?
EN(H4SO)(diag)-89
ENGINE (DIAGNOSTICS)
Yes
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 the rear
and connector. oxygen sensor.
<Ref. to
NOTE:
FU(H4SO)-45,
In this case, repair
Rear Oxygen Sen-
the following:
sor.>
• 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