Subaru Legacy 2002 Service Manual page 1513

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Engine (DIAGNOSTICS)
No.
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start engine, and warm-up the engine.
2) Turn ignition switch to OFF.
3) Disconnect connectors from ECM and front
oxygen (A/F) sensor.
4) Measure resistance of harness between
ECM and front oxygen (A/F) sensor connec-
tor.
Connector & terminal
(B137) No. 6 — (E24) No. 1:
(B137) No. 7 — (E24) No. 1:
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure resistance of harness between ECM
and front oxygen (A/F) sensor connector.
Connector & terminal
(B137) No. 20 — (E24) No. 4:
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure resistance of harness between ECM
and front oxygen (A/F) sensor connector.
Connector & terminal
(B137) No. 30 — (E24) No. 3:
4 CHECK FRONT OXYGEN (A/F) SENSOR.
Measure resistance between front oxygen
(A/F) sensor connector terminals.
Terminals
No. 2 — No. 1:
5 CHECK POOR CONTACT.
Check poor contact in ECM and front oxygen
(A/F) sensor connector.
Step
Is the resistance less than
1 Ω?
Is the resistance less than
1 Ω?
Is the resistance less than
1 Ω?
Is the resistance less than
5 Ω?
Is there poor contact in
ECM or front oxygen (A/F)
sensor connector?
EN(H6)-306
Check Yes
Go to step 2.
Go to step 3.
Go to step 4.
Go to step 5.
Repair poor con-
tact in ECM or
front oxygen (A/F)
sensor connector.
No
Repair open cir-
cuit in harness
between ECM
and front oxygen
(A/F) sensor con-
nector.
Repair open cir-
cuit in harness
between ECM
and front oxygen
(A/F) sensor con-
nector.
Repair open cir-
cuit in harness
between ECM
and front oxygen
(A/F) sensor con-
nector.
Replace front oxy-
gen (A/F) sensor.
<Ref. to FU(H6)-
43, Front Oxygen
(A/F) Sensor.>
Replace front oxy-
gen (A/F) sensor.
<Ref. to FU(H6)-
43, Front Oxygen
(A/F) Sensor.>