Subaru Legacy 2003 Service Manual page 2024

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) sen-
sor connector.
Connector & terminal
(B137) No. 29 — (B18) No. 3:
(B137) No. 19 — (B18) No. 4:
Is the measured value less than the speci-
fied value?
2 CHECK POOR CONTACT.
Check poor contact in front oxygen (A/F) sen-
sor connector.
Is there poor contact in front oxygen (A/F) sen-
sor connector?
Value
1 Ω
There is poor contact.
EN(H4DOSTC)-185
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and front
oxygen (A/F) sen-
sor connector
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
ECM connector
Repair the poor Replace the front
contact in front oxygen (A/F) sen-
oxygen (A/F) sen- sor. <Ref. to
sor connector. FU(H4DOSTC)-
38, Front Oxygen
(A/F) Sensor.>
No