Subaru Impreza 2003 Service Manual page 1269

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
LHD model
(B19) No. 2 (+) — Chassis ground ( − − − − ):
RHD model
(B19) No. 1 (+) — 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(H4DOTC)-93
ENGINE (DIAGNOSTICS)
Yes
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(H4DOTC)-46,
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