Subaru 2002 IMPREZA Service Manual page 531

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
30 to step
3 .
Step
CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (NF) SENSOR CONNEC-
TOR.
1)Start the engine, and warm-up the engine.
2)Turn the ignition switch to OFF.
3)Disconnect the connectors from ECM and
front oxygen (NF) sensor.
4)Measure the resistance of harness between
ECM and front oxygen (NF) sensor connector.
Connector & terminal
(8137) NO. 5
-
(818) NO. 1:
(8137) NO. 4
-
(818) NO. 1:
I
CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN ( N F ) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
ECM and front oxygen (NF) sensor connector.
Connector & terminal
(8137) NO. 19
-
(818)
NO.
4:
(8137) NO. 29
-
(818) NO. 3:
I
CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN ( N F ) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
main relay and front oxygen (NF) sensor con-
nector.
Connector & terminal
(847) NO. 4
-
(818) NO. 2:
I
CHECK FRONT OXYGEN
(NF)
SENSOR.
Measure the resistance between front oxygen
(NF) sensor connector terminals.
Terminals
NO. 2 -NO. 1:
Repair open circuit
in harness
between ECM and
front oxygen (NF)
sensor connector.
i
CHECK POOR CONTACT.
Check poor contact in ECM and front oxygen
(NF) sensor connector.
30 to step 4.
30 to step 5.
Repair poor con-
tact in ECM or
iront oxygen (NF)
sensor connector.
Check
Repair open circuil
in harness
between ECM and
front oxygen (NF)
sensor connector.
Replace the front
oxygen (NF) sen-
sor. <Ref. to
FU( DOHC
TURBO)-42, Front
Oxygen (NF) Sen
sor.>
Replace the front
oxygen (NF) sen-
sor. <Ref. to
FU(D0HC
TURBO)-42, Fronl
Oxygen (NF) Sen
sor.>
s the resistance less than 1
L?
s the resistance less than 1
2?
s
the resistance less than 1
2?
s
the resistance less than 5
2?
s
there poor contact in ECM or
ront oxygen (NF) sensor con-
lector?
EN(D0HC TURBO)-307
in harness
between ECM and
front oxygen (NF)
sensor connector.
I