Subaru Legacy 2003 Service Manual page 544

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure voltage of harness between ECM
connector and chassis ground.
Connector & terminal
(B136) No. 13 (+) — Chassis ground (-):
(B136) No. 22 (+) — Chassis ground (-):
Does the measured value exceed the spec-
ified value?
Value
8 V
EN(H4SO)-147
ENGINE (DIAGNOSTICS)
Yes
Replace front oxy- Repair battery
gen (A/F) sensor. short circuit in har-
<Ref. to ness between
FU(H4SO)-43, ECM and front
Rear Oxygen Sen- oxygen (A/F) sen-
sor.> sor connector.
No