2001 INFINITI QX4 check engine

12 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. 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.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
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 14.
NG©GO TO 13.
13 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
©Replace malfunctioning heated oxygen sensor 1 (front).
14 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
DTC P0133, P0153 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(RESPONSE MONITORING)
Diagnostic Procedure (Cont'd)
EC-230

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
SEF301UA
On Board Diagnosis LogicNBEC0119To judge the malfunction, the diagnosis checks that the heated
oxygen sensor 1 (front) output is not inordinately high.
Malfunction is detected when an excessively high voltage from the
sensor is sent to ECM.
Possible CauseNBEC0436IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 1 (front)
SEF174Y
DTC Confirmation ProcedureNBEC0120NOTE:
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-IINBEC0120S011) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 10 seconds.
3) Turn ignition switch ªONº.
4) Select ªDATA MONITORº mode with CONSULT-II.
DTC P0134, P0154 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
ECM Terminals and Reference Value (Cont'd)
EC-232

5 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªMANU TRIGº and adjust ªTRIGGER POINTº to 100% in ªDATA MONITORº mode with CONSULT-II.
3. Select ªHO2S1 (B1)/(B2)º and ªHO2S1 MNTR (B1)/(B2)º.
4. Hold engine speed at 2,000 rpm under no load during the following steps.
5. Touch ªRECORDº on CONSULT-II screen.
SEF967Y
6. Check the following.
IªHO2S1 MNTR (B1)/(B2)º in ªDATA MONITORº mode changes from ªRICHº to ªLEANº to ªRICHº 5 times in 10 seconds.
5 times (cycles) are counted as shown left:
SEF647Y
IªHO2S1 (B1)/(B2)º voltage goes above 0.6V at least once.
IªHO2S1 (B1)/(B2)º voltage goes below 0.3V at least once.
IªHO2S1 (B1)/(B2)º voltage never exceeds 1.0V.
SEF648Y
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 8.
NG©GO TO 7.
DTC P0134, P0154 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-238

6 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. 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.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
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 8.
NG©GO TO 7.
7 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
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 1 (front).
8 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0134, P0154 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-239

Possible CauseNBEC0438IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 2 (rear)
IFuel pressure
IInjectors
SEF340Z
SEF341Z
SEF342Z
DTC Confirmation ProcedureNBEC0134NOTE:
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:
Open engine hood before conducting following procedure.
WITH CONSULT-IINBEC0134S011) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 10 seconds.
3) Turn ignition switch ªONº.
4) Select ªDATA MONITORº mode with CONSULT-II.
5) Make sure that ªCOOLAN TEMP/Sº indicates more than 70ÉC
(158ÉF).
6) Select ªHO2S2 (B1)/(B2) P0137/P0157º of ªHO2S2º in ªDTC
WORK SUPPORTº mode with CONSULT-II.
7) Start engine and follow the instruction of CONSULT-II.
8) Make sure that ªOKº is displayed after touching ªSELF-DIAG
RESULTSº.
If NG is displayed, refer to ªDiagnostic Procedureº, EC-252.
If ªCANNOT BE DIAGNOSEDº is displayed, perform the fol-
lowing.
a) Stop engine and cool down until ªCOOLAN TEMP/Sº indicates
less than 70ÉC (158ÉF).
b) Turn ignition switch ªONº.
c) Select ªDATA MONITORº mode with CONSULT-II.
d) Start engine.
e) Return to step 6 again when the ªCOOLAN TEMP/Sº reaches
to 70ÉC (158ÉF).
SEF312XB
Overall Function CheckNBEC0135Use this procedure to check the overall function of the heated oxy-
gen sensor 2 (rear) circuit. During this check, a 1st trip DTC might
not be confirmed.
WITH GSTNBEC0135S011) 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
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Possible Cause
EC-248

1 right signal) or 71 (HO2S2 bank 2 left signal) and engine
ground.
4) Check the voltage when racing up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be below 0.57V at least once during
this procedure.
If the voltage can be confirmed in step 4, step 5 is not
necessary.
5) Keep vehicle at idling for 10 minutes, then check the voltage.
Or check the voltage when coasting from 80 km/h (50 MPH)
in ªDº position with ªODº OFF.
The voltage should be below 0.57V at least once during
this procedure.
6) If NG, go to ªDiagnostic Procedureº, EC-252.
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DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Overall Function Check (Cont'd)
EC-249

4 CHECK HO2S2 (REAR) GROUND CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between HO2S2 terminal 4 and engine ground.
Refer to Wiring Diagram.
Continuity should exist.
2. Also check harness for short to power.
OK or NG
OK (With CONSULT-II)©GO TO 5.
OK (Without CONSULT-
II)©GO TO 6.
NG©Repair open circuit or short to power in harness or connectors.
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.
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Diagnostic Procedure (Cont'd)
EC-254

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 rewing 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.
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 ignitioin switch OFF.
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).
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IDX
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Diagnostic Procedure (Cont'd)
EC-255