Subaru Legacy 2004 Service Manual page 887

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK OPTION CODE.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector 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
(B134) No. 26 — (E24) No. 1:
(B134) No. 33 — (E24) No. 3:
3 CHECK POOR CONTACT.
Check poor contact in front oxygen (A/F) sen-
sor connector.
Check
Is the option code EC, EK or
K4?
Is the resistance less than 1
!?
Is there poor contact in front
oxygen (A/F) sensor connec-
tor?
EN(H4SO 2.5)(diag)-128
Yes
Go to step 2. Refer to EN(H4SO
2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
Go to step 3. 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(H4SO 2.5)-34,
Front Oxygen (A/
F) Sensor.>
No