Subaru 2002 Impreza - Page 313

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
CHECK ANY OTHER DTC ON DISPLAY.
CHECK POWER SUPPLY TO FRONT
OXY-
GEN (NF) SENSOR.
1)Turn the ignition switch to
OFF.
2)Disconnect the connector from front oxygen
(NF) sensor.
3)Turn the ignition switch to ON.
4)Measure the voltage between front oxygen
(NF) sensor connector and engine ground.
Connector & terminal
(8 18) No. 2 (+) - Engine ground (-):
CHECK GROUND CIRCUIT OF ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(8137)
No. 8 - Chassis ground:
(8137)
No. 9 - Chassis ground:
CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of front oxygen
(NF) sensor
heater current using Subaru Select Monitor or
OBD-ll general scan tool.
NOTE:
*Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA
FOR ENGINE. <Ref.
to EN(D0HC TURBO)-38, Subaru Select Mon
itor.>
*OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan
Tool Instruction Manual.
CHECK OUTPUT SIGNAL FROM ECM.
1)Start and idle the engine.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
.
(8137) No. 4 (+) - Chassis ground (-):
(8137) No. 5 (+) - Chassis ground (-):
CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(8 137) No. 4 (+) - Chassis ground (-)I
(8137) No. 5 (+) - Chassis ground (-)I
Check
)oes the Subaru Select Moni-
3r or OBD-II general scan tool
idicate DTC PO031 and
’0037 at the same time?
s the voltage more than 10 V?
s the resistance less than 5
2?
s the value more than 0.2 A?
s the voltage less than 1 .O V?
Ioes the voltage change less
han 1
.O V by shaking harness
md connector of ECM while
nonitoring the value with volt-
ige meter?
Yes
io to step 2.
io to step 3.
;o to step 4.
3epair poor con-
act in connector.
JOTE:
n this case, repaii
he following:
I Poor contact in
ront oxygen (NF)
jensor connector
1 Poor contact in
ECM connector
30 to step 7.
3epair poor con-
act in ECM con-
lector.
No
Go to step 5.
Repair power sup-
ply line.
NOTE:
In this case, repaii
the following:
* Open circuit in
harness between
main relay and
front oxygen
(NF)
sensor connector
* Poor contact in
front oxygen
(NF)
sensor connector
Poor contact in
main relay connec.
tor
Repair harness
and connector.
NOTE:
In this case, repaii
the following:
Open circuit in
harness between
ECM and engine
ground terminal
9 Poor contact in
ECM connector
Poor contact in
coupling connectoi
Go to step 5.
Go to step 6.
Go to step 7.
EN(D0HC TURBO)-89