2001 INFINITI QX4 Engine control

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
SEF010V
On Board Diagnosis LogicNBEC0111To judge the malfunction of heated oxygen sensor 1 (front), this
diagnosis measures response time of heated oxygen sensor 1
(front) signal. The time is compensated by engine operating (speed
and load), fuel feedback control constant, and heated oxygen sen-
sor 1 (front) temperature index. Judgment is based on whether the
compensated time [heated oxygen sensor 1 (front) cycling time
index] is inordinately long or not.
Malfunction is detected when the response of the voltage signal
from the sensor takes more than the specified time.
Possible CauseNBEC0435IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 1 (front)
IHeated oxygen sensor 1 heater (front)
IFuel pressure
IInjectors
IIntake air leaks
IExhaust gas leaks
IPCV valve
IMass air flow sensor
GI
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DTC P0133, P0153 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(RESPONSE MONITORING)
ECM Terminals and Reference Value (Cont'd)
EC-219

5 CLEAR THE SELF-LEARNING DATA
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªSELF-LEARNING CONTº in ªWORK SUPPORTº mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching ªCLEARº.
SEF968Y
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure 1st trip DTC P0100 is displayed.
6. Erase the 1st trip DTC memory. Refer to ªHOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATIONº,
EC-72.
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?
YesorNo
Ye s©Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to EC-294,
302.
No©GO TO 6.
GI
MA
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LC
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PD
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SU
BR
ST
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HA
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IDX
DTC P0133, P0153 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(RESPONSE MONITORING)
Diagnostic Procedure (Cont'd)
EC-225

DescriptionNBEC0123SYSTEM DESCRIPTIONNBEC0123S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speedHeated
oxygen
sensor 1
heater
(front) con-
trolHeated oxygen sensor 1 heat-
ers (front)
Crankshaft position sensor (REF)
The ECM performs ON/OFF control of the heated oxygen sensor 1 heaters (front) corresponding to the engine
speed.
OPERATIONNBEC0123S02
Engine speed rpm Heated oxygen sensor 1 heaters (front)
Above 3,600 OFF
Below 3,600 ON
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0124Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S1 HTR (B1)
HO2S1 HTR (B2)IEngine speed: Below 3,600 rpm ON
IEngine speed: Above 3,600 rpm OFF
ECM Terminals and Reference ValueNBEC0657Specification 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)
3 L/ORHeated oxygen sensor
1 heater (front) (bank
1)[Engine is running]
IEngine speed is below 3,600 rpm.0 - 1.0V
[Engine is running]
IEngine speed is above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)
2 R/GHeated oxygen sensor
1 heater (front) (bank
2)[Engine is running]
IEngine speed is below 3,600 rpm.0 - 1.0V
[Engine is running]
IEngine speed is above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)
DTC P0135, P0155 HEATED OXYGEN SENSOR 1 HEATER (FRONT) (BANK
1)/(BANK 2)
Description
EC-240

SEF327R
Component DescriptionNBEC0130The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0131Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
IEngine: After warming upRevving engine from idle up to
2,000 rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)
HO2S2 MNTR
(B2)LEAN+,RICH
ECM Terminals and Reference ValueNBEC0658Specification 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)
72 ORHeated oxygen sensor
2 (rear) (bank 1)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
71 OR/LHeated oxygen sensor
2 (rear) (bank 2)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
SEF304UB
On Board Diagnosis LogicNBEC0133The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the mini-
mum voltage of sensor is sufficiently low during the various driving
condition such as fuel-cut.
Malfunction is detected when the minimum voltage from the sen-
sor is not reached to the specified voltage.
GI
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IDX
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Component Description
EC-247

Diagnostic ProcedureNBEC0137
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 2.
2 CLEAR THE SELF-LEARNING DATA
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªSELF-LEARNING CONTº in ªWORK SUPPORTº mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching ªCLEARº.
SEF968Y
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 or P0175 detected?
Is it difficult to start engine?
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure 1st trip DTC P0100 is displayed.
6. Erase the 1st trip DTC memory. Refer to ªHOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATIONº,
EC-72.
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 or P0175 detected?
Is it difficult to start engine?
YesorNo
Ye s©Perform trouble diagnosis for DTC P0172, P0175. Refer to EC-302.
No©GO TO 3.
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Diagnostic Procedure
EC-252

SEF327R
Component DescriptionNBEC0138The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0139Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
IEngine: After warming upRevving engine from idle up to
2,000 rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)
HO2S2 MNTR
(B2)LEAN+,RICH
ECM Terminals and Reference ValueNBEC0659Specification 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)
72 ORHeated oxygen sensor
2 (rear) (bank 1)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
71 OR/LHeated oxygen sensor
2 (rear) (bank 2)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
SEF303UB
On Board Diagnosis LogicNBEC0141The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the maxi-
mum voltage of the sensor is sufficiently high during the various
driving condition such as fuel-cut.
Malfunction is detected when the maximum voltage from the sen-
sor is not reached to the specified voltage.
GI
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PD
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ST
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IDX
DTC P0138, P0158 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MAX. VOLTAGE MONITORING)
Component Description
EC-257

Diagnostic ProcedureNBEC0145
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 2.
2 CLEAR THE SELF-LEARNING DATA
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªSELF-LEARNING CONTº in ªWORK SUPPORTº mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching ªCLEARº.
SEF968Y
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 or P0174 detected?
Is it difficult to start engine?
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure 1st trip DTC P0100 is displayed.
6. Erase the 1st trip DTC memory. Refer to ªHOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATIONº,
EC-72.
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 or P0174 detected?
Is it difficult to start engine?
YesorNo
Ye s©Perform trouble diagnosis for DTC P0171, P0174. Refer to EC-294.
No©GO TO 3.
DTC P0138, P0158 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MAX. VOLTAGE MONITORING)
Diagnostic Procedure
EC-262

SEF327R
Component DescriptionNBEC0146The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0147Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
IEngine: After warming upRevving engine from idle up to
2,000 rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)
HO2S2 MNTR
(B2)LEAN+,RICH
ECM Terminals and Reference ValueNBEC0660Specification 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)
72 ORHeated oxygen sensor
2 (rear) (bank 1)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
71 OR/LHeated oxygen sensor
2 (rear) (bank 2)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
SEF302U
On Board Diagnosis LogicNBEC0149The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the switch-
ing response of the sensor's voltage is faster than specified during
the various driving condition such as fuel-cut.
Malfunction is detected when it takes more time for the sensor to
respond between rich and lean than the specified time.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0139, P0159 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(RESPONSE MONITORING)
Component Description
EC-267