IDX INFINITI QX4 2001 Factory Service Manual

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
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DTC P0125 ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
Diagnostic Procedure (Cont'd)
EC-191

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)
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DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
ECM Terminals and Reference Value (Cont'd)
EC-193

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.
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DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Overall Function Check (Cont'd)
EC-195

LEFT BANKNBEC0092S02
MEC948C
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DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Wiring Diagram (Cont'd)
EC-197

2 CHECK HO2S1 (FRONT) INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S1 terminal as follows.
Refer to Wiring Diagram.
MTBL0471
Continuity should exist.
3. Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows.
Refer to Wiring Diagram.
MTBL0472
Continuity should not exist.
4. Also check harness for short to power.
OK or NG
OK (With CONSULT-II)©GO TO 3.
OK (Without CONSULT-
II)©GO TO 4.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
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DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-199

4 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 6.
NG©GO TO 5.
5 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).
6 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0130, P0150 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-201

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
SEF300U
On Board Diagnosis LogicNBEC0097To judge the malfunction, the output from the heated oxygen sen-
sor 1 (front) is monitored to determine whether the ªrichº output is
sufficiently high and whether the ªleanº output is sufficiently low.
When both the outputs are shifting to the lean side, the malfunc-
tion will be detected.
Malfunction is detected when the maximum and minimum voltage
from the sensor are not reached to the specified voltages.
Possible CauseNBEC0433IHeated oxygen sensor 1 (front)
IHeated oxygen sensor 1 heater (front)
IFuel pressure
IInjectors
IIntake air leaks
DTC Confirmation ProcedureNBEC0098CAUTION:
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:
IAlways perform at a temperature above þ10ÉC (14ÉF).
IBefore performing following procedure, confirm that bat-
tery voltage is more than 11V at idle.
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DTC P0131, P0151 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(LEAN SHIFT MONITORING)
ECM Terminals and Reference Value (Cont'd)
EC-203

Diagnostic ProcedureNBEC0100
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 2.
2 RETIGHTEN HEATED OXYGEN SENSOR 1 (FRONT)
Loosen and retighten corresponding heated oxygen sensor 1 (front).
Tightening torque:
40 - 60 N´m (4.1 - 6.1 kg-m, 30 - 44 ft-lb)
©GO TO 3.
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DTC P0131, P0151 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(LEAN SHIFT MONITORING)
Diagnostic Procedure
EC-205

4 CHECK HEATED OXYGEN SENSOR HEATER 1 (FRONT)
1. Stop engine.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
3. Disconnect HO2S1 harness connector.
4. Check resistance between HO2S1 terminals as follows.
SEF969Y
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 (With CONSULT-II)©GO TO 5.
OK (Without CONSULT-
II)©GO TO 6.
NG©GO TO 7.
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DTC P0131, P0151 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(LEAN SHIFT MONITORING)
Diagnostic Procedure (Cont'd)
EC-207

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 FRONT HEATED OXYGEN SENSOR
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.
For circuit, refer to ªDTC P0130 (RIGHT BANK 1), P0150 (LEFT BANK 2) HEATED OXYGEN SENSOR 1 (FRONT)
[HO2S1 (FRONT) (BANK 1)/(BANK 2)] (CIRCUIT)º, EC-192.
©INSPECTION END
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DTC P0131, P0151 HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1)/(BANK 2)
(LEAN SHIFT MONITORING)
Diagnostic Procedure (Cont'd)
EC-209