2001 INFINITI QX4 02 sensor

5 CHECK HEATED OXYGEN SENSOR 2 (REAR)
With CONSULT-II
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Select ªFUEL INJECTIONº in ªACTIVE TESTº mode, and select ªHO2S2 (B1)/(B2)º as the monitor item with CONSULT-
II.
4. Check ªHO2S2 (B1)/(B2)º at idle speed when adjusting ªFUEL INJECTIONº to±25%.
SEF972Y
ªHO2S2 (B1)/(B2)º should be above 0.62V at least once when the ªFUEL INJECTIONº is +25%.
ªHO2S2 (B1)/(B2)º should be below 0.57V at least once when the ªFUEL INJECTIONº is þ25%.
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 9.
NG©GO TO 8.
6 CHECK HEATED OXYGEN SENSOR 2 (REAR)-I
Without CONSULT-II
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminal 72 (HO2S2 bank 1 right signal) or 71 (HO2S2 bank 2 left signal) and
engine ground.
4. Check the voltage when revving up to 4,000 rpm under no load at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
SEF313XA
OK or NG
OK©GO TO 9.
NG©GO TO 7.
DTC P0140, P0160 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-284

7 CHECK HEATED OXYGEN SENSOR 2 (REAR)-II
Idle vehicle for 10 minutes, then check voltage between the same terminals as in Test No. 6; or check voltage when coast-
ing from 80 km/h (50 MPH) in ªDº position with ªODº OFF.
The voltage should go below 0.57V at least once during this procedure.
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 9.
NG©GO TO 8.
8 REPLACE HEATED OXYGEN SENSOR 2 (REAR)
1. Stop vehicle and turn ignition switch ªOFFº.
2. Check heated oxygen sensor 2 (rear) harness protector color.
SEF372Z
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 2 (rear).
9 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0140, P0160 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-285

DescriptionNBEC0162SYSTEM DESCRIPTIONNBEC0162S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speedHeated
oxygen
sensor 2
heater
(rear) con-
trolHeated oxygen sensor 2 heat-
ers (rear)
Crankshaft position sensor (REF)
The ECM performs ON/OFF control of the heated oxygen sensor 2 heaters (rear) corresponding to the engine
speed.
OPERATIONNBEC0162S02
Engine speed rpm Heated oxygen sensor 2 heaters (rear)
Above 3,200 OFF
Below 3,200 ON
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0163Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 HTR (B1)
HO2S2 HTR (B2)IIgnition switch: ON (Engine stopped)
IEngine is running above 3,200 rpm.OFF
IEngine is running below 3,200 rpm after driving for 2 minutes at a
speed of 70 km/h (43 MPH) or more.ON
ECM Terminals and Reference ValueNBEC0662Specification 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)
5 P/BHeated oxygen sensor
2 heater (rear) (bank
1)[Engine is running]
IEngine speed is below 3,200 rpm.
IAfter driving for 2 minutes at a speed of 70 km/h
(43 MPH) or more.0 - 1.0V
[Ignition switch ªONº]
IEngine stopped
[Engine is running]
IEngine speed is above 3,200 rpm.BATTERY VOLTAGE
(11 - 14V)
4 R/WHeated oxygen sensor
2 heater (rear) (bank
2)[Engine is running]
IEngine speed is below 3,200 rpm.
IAfter driving for 2 minutes at a speed of 70 km/h
(43 MPH) or more.0 - 1.0V
[Ignition switch ªONº]
IEngine stopped
[Engine is running]
IEngine speed is above 3,200 rpm.BATTERY VOLTAGE
(11 - 14V)
DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Description
EC-286

On Board Diagnosis LogicNBEC0165Malfunction is detected when the current amperage in the heated
oxygen sensor 2 heater (rear) circuit is out of the normal range.
[An improper voltage drop signal is sent to ECM through the heated
oxygen sensor 2 heater (rear).]
Possible CauseNBEC0442IHarness or connectors
[The heated oxygen sensor 2 heater (rear) circuit is open or
shorted.]
IHeated oxygen sensor 2 heater (rear)
SEF058Y
DTC Confirmation ProcedureNBEC0166NOTE:
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 between 10.5V and 16V at idle.
WITH CONSULT-IINBEC0166S011) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine.
3) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
4) Stop vehicle and let engine idle for at least 6 seconds.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-291.
WITH GSTNBEC0166S021) Start engine.
2) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
3) Stop vehicle and let engine idle for at least 6 seconds.
4) Turn ignition switch ªOFFº and wait at least 10 seconds.
5) Start engine.
6) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
7) Stop vehicle and let engine idle for at least 6 seconds.
8) Select ªMODE 3º with GST.
9) If DTC is detected, go to ªDiagnostic Procedureº, EC-291.
IWhen using GST, ªDTC Confirmation Procedureº should
be performed twice as much as when using CONSULT-II
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DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
On Board Diagnosis Logic
EC-287

because GST cannot display MODE 7 (1st trip DTC) con-
cerning this diagnosis. Therefore, using CONSULT-II is
recommended.
DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
DTC Confirmation Procedure (Cont'd)
EC-288

Wiring DiagramNBEC0167RIGHT BANKNBEC0167S01
MEC953C
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DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Wiring Diagram
EC-289

LEFT BANKNBEC0167S02
MEC954C
DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Wiring Diagram (Cont'd)
EC-290

Diagnostic ProcedureNBEC0168
1 CHECK HO2S2 (REAR) POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor harness 2 (rear) protector color.
SEF372Z
3. Disconnect corresponding heated oxygen sensor 2 (rear) harness connector.
SEF971Y
4. Turn ignition switch ªONº.
5. Check voltage between HO2S2 terminal 3 and ground.
SEF314X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors M32, F23
IFuse block (J/B) connector M10
I15A fuse
IHarness for open or short between heated oxygen sensor 2 (rear) and fuse
©Repair harness or connectors.
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DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Diagnostic Procedure
EC-291