02 sensor INFINITI QX4 2001 Factory Service Manual

Possible CauseNBEC0431IHarness or connectors
(High resistance in the circuit)
IEngine coolant temperature sensor
IThermostat
SEF174Y
DTC Confirmation ProcedureNBEC0083CAUTION:
Be careful not to overheat engine.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
WITH CONSULT-IINBEC0083S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Check that ªCOOLAN TEMP/Sº is above 10ÉC (50ÉF).
If it is above 10ÉC (50ÉF), the test result will be OK.
If it is below 10ÉC (50ÉF), go to following step.
4) Start engine and run it for 65 minutes at idle speed.
If ªCOOLAN TEMP/Sº increases to more than 10ÉC (50ÉF)
within 65 minutes, stop engine because the test result will
be OK.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-190.
WITH GSTNBEC0083S02Follow the procedure ªWITH CONSULT-IIº above.
DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Possible Cause
EC-188

Wiring DiagramNBEC0084
MEC945C
GI
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DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Wiring Diagram
EC-189

Diagnostic ProcedureNBEC0085
1 CHECK ECTS POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor harness connector F112, F28.
SEF370Z
3. Turn ignition switch ªONº.
4. Check voltage between ECTS harness connector F28 terminal 3 and ground with CONSULT-II or tester.
SEF371Z
OK or NG
OK©GO TO 3.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open or short between ECM and engine coolant temperature sensor
©Repair harness or connectors.
3 CHECK ECTS GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between ECTS terminal 2 and engine ground.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Diagnostic Procedure
EC-190

4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open between ECM and engine coolant temperature sensor
IHarness for open between TCM (Transmission Control Module) and engine coolant temperature sensor
©Repair open circuit or short to power in harness or connectors.
5 CHECK ENGINE COOLANT TEMPERATURE SENSOR
Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.
SEF304X
OK or NG
OK©GO TO 6.
NG©Replace engine coolant temperature sensor.
6 CHECK THERMOSTAT OPERATION
When the engine is cold [lower than 70ÉC (158ÉF)] condition, grasp lower radiator hose and confirm the engine coolant
does not flow.
OK or NG
OK©GO TO 7.
NG©Repair or replace thermostat. Refer to LC-16, ªThermostatº.
7 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
GI
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DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Diagnostic Procedure (Cont'd)
EC-191

SEF463R
SEF288D
Component DescriptionNBEC0086The heated oxygen sensor 1 (front) is placed into the front tube. It
detects the amount of oxygen in the exhaust gas compared to the
outside air. The heated oxygen sensor 1 (front) has a closed-end
tube made of ceramic zirconia. The zirconia generates voltage from
approximately 1V in richer conditions to 0V in leaner conditions.
The heated oxygen sensor 1 (front) signal is sent to the ECM. The
ECM adjusts the injection pulse duration to achieve the ideal air-
fuel ratio. The ideal air-fuel ratio occurs near the radical change
from 1V to 0V.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0087Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S1 (B1)
HO2S1 (B2)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S1 MNTR
(B1)
HO2S1 MNTR
(B2)LEAN+,RICH
Changes more than 5 times during
10 seconds.
ECM Terminals and Reference ValueNBEC0652Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
63 GHeated oxygen sensor
1 (front) (bank 1)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V (Peri-
odically change)
SEF059V
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Component Description
EC-192

TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
62 G/BHeated oxygen sensor
1 (front) (bank 2)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V (Peri-
odically change)
SEF059V
SEF237U
On Board Diagnosis LogicNBEC0089Under the condition in which the heated oxygen sensor 1 (front)
signal is not input, the ECM circuits will read a continuous approxi-
mately 0.3V. Therefore, for this diagnosis, the time that output
voltage is within 200 to 400 mV range is monitored, and the diag-
nosis checks that this time is not inordinately long.
Malfunction is detected when the voltage from the sensor is con-
stantly approx. 0.3V.
Possible CauseNBEC0432IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 1 (front)
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
ECM Terminals and Reference Value (Cont'd)
EC-193

SEF332Z
DTC Confirmation ProcedureNBEC0090
SEF333Z
SEF645Y
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is more than 11V at idle.
WITH CONSULT-IINBEC0090S011) Start engine and warm it up to normal operating temperature.
2) Select ªHO2S1 (B1)/(B2) P0130/P0150º of ªHO2S1º in ªDTC
WORK SUPPORTº mode with CONSULT-II.
3) Touch ªSTARTº.
4) Let it idle for at least 3 minutes.
NOTE:
Never raise engine speed above 3,600 rpm after this step. If
the engine speed limit is exceeded, return to step 4.
5) When the following conditions are met, ªTESTINGº will be dis-
played on the CONSULT-II screen. Maintain the conditions
continuously until ªTESTINGº changes to ªCOMPLETEDº. (It
will take approximately 10 to 60 seconds.)
ENG SPEED 1,500 - 2,800 rpm
Vehicle speed 70 - 100 km/h (43 - 62 MPH)
B/FUEL SCHDL 3.0 - 10 msec
Selector lever Suitable position
If ªTESTINGº is not displayed after 5 minutes, retry from
step 2.
6) Make sure that ªOKº is displayed after touching ªSELF-DIAG
RESULTSº. If ªNGº is displayed, refer to ªDiagnostic
Procedureº, EC-198.
During this test, P1148 and P1168 may be stored in ECM.
SEF308XB
Overall Function CheckNBEC0091Use this procedure to check the overall function of the heated oxy-
gen sensor 1 (front) circuit. During this check, a 1st trip DTC might
not be confirmed.
WITH GSTNBEC0091S011) Start engine and warm it up to normal operating temperature.
2) Set voltmeter probes between ECM terminal 63 (HO2S1 bank
1 right signal) or 62 (HO2S1 bank 2 left signal) and engine
ground.
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
DTC Confirmation Procedure
EC-194

3) Check the following with engine speed held at 2,000 rpm con-
stant under no load.
IThe voltage does not remain in the range of 0.2 - 0.4V.
4) If NG, go to ªDiagnostic Procedureº, EC-198.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Overall Function Check (Cont'd)
EC-195

Wiring Diagram=NBEC0092RIGHT BANKNBEC0092S01
MEC947C
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Wiring Diagram
EC-196

LEFT BANKNBEC0092S02
MEC948C
GI
MA
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LC
FE
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PD
AX
SU
BR
ST
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BT
HA
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IDX
DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Wiring Diagram (Cont'd)
EC-197