Subaru Legacy 2004 Service Manual page 890

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
5 CHECK HARNESS BETWEEN REAR OXY-
GEN SENSOR AND ECM CONNECTOR.
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 harness connector and chassis ground.
Connector & terminal
(B19) No. 3 (+) — Chassis ground (
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items:
• Loose part of exhaust system and incom-
plete installation
• Damage (crack, hole etc.) of parts
• Looseness and ill fitting of parts between
front oxygen (A/F) sensor and rear oxygen
sensor
Check
Is the voltage 0.2 — 0.5 V?
"
):
Is there any fault in exhaust
system?
EN(H4SO 2.5)(diag)-131
ENGINE (DIAGNOSTICS)
Yes
Replace the rear Repair the har-
oxygen sensor. ness and connec-
<Ref. to FU(H4SO tor.
2.5)-35, Rear Oxy-
NOTE:
gen Sensor.>
In this case, repair
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
Repair or replace Replace the rear
the faulty part. oxygen sensor.
<Ref. to FU(H4SO
2.5)-35, Rear Oxy-
gen Sensor.>
No