Subaru Impreza 2003 Service Manual page 539

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connectors from ECM and
front oxygen (A/F) sensor connector.
3)Measure the resistance of harness between
ECM and front oxygen (A/F) sensor connector.
Connector & terminal
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:
Check
Is the resistance more than 1
MΩ?
EN(H4SO)-127
ENGINE (DIAGNOSTICS)
Yes
Replace the front Repair ground
oxygen (A/F) sen- short circuit in har-
sor. <Ref. to ness between
FU(H4SO)-44, ECM and front
Front Oxygen (A/ oxygen (A/F) sen-
F) Sensor.> sor connector.
No