2008 INFINITI QX56 engine

EC-136
< COMPONENT DIAGNOSIS >[VK56DE]
P0127 IAT SENSOR
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Start engine.
5. Hold vehicle speed at more than 70 km/h (43 MPH) for 100 consecutive seconds.
6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to
EC-136, "
Diagnosis Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001351449
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-86, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK INTAKE AIR TEMPERATURE SENSOR
Refer to EC-136, "
Component Inspection" .
OK or NG
OK >> GO TO 3.
NG >> Replace mass air flow sensor (with intake air temperature sensor).
3.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
Refer to EC-439, "
Wiring Diagram - ENGINE CONTROL SYSTEM -" .
>> INSPECTION END
Component InspectionINFOID:0000000001351450
INTAKE AIR TEMPERATURE SENSOR
1. Check resistance between intake air temperature sensor termi-
nals 5 and 6 under the following conditions.
2. If NG, replace mass air flow sens or (with intake air temperature
sensor).
BBIA0354E
Intake air temperature °C ( °F) Resistance k Ω
25 (77) 1.800 - 2.200
BBIA0355E
Revision: March 2010 2008 QX56

EC-138
< COMPONENT DIAGNOSIS >[VK56DE]
P0128 THERMOSTAT FUNCTION
P0128 THERMOSTAT FUNCTION
On Board Diagn
osis LogicINFOID:0000000001449652
NOTE:
If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308,
first perform the trouble diagnosis for DTC P 0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307,
P0308. Refer to EC-198, "
DTC Confirmation Procedure".
Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long
enough.
This is due to a leak in the seal or the thermostat stuck open.
DTC Confirmation ProcedureINFOID:0000000001449653
NOTE:
Check vehicle specifications and VIN, then select the procedure to be performed. (Refer to the table below.)
PROCEDURE A
With CONSULT-III
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
•For best results, perform at ambient temperature of –10 °C (14° F) or higher.
• For best results, perform at en gine coolant temperature of –10 °C (14° F) to 71 °C (160 °F).
• Before performing the following procedure, do not fill with the fuel.
1. Turn A/C switch OFF.
2. Turn blower fan switch OFF.
3. Turn ignition switch ON.
4. Select “COOLAN TEMP/S” in “DATA MONITOR” mode with CONSULT-III.
5. Check the indication of “COOLAN TEMP/S”. If it is below 71 °C (160° F), go to following step.
If it is above 71 °C (160° F), cool down the engine to less than 71 °C (160° F). Then go to next steps.
6. Start engine and wait at idle for at least 30 minutes.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0128
0128 Thermostat function The engine coolant temperature does not
reach to specified temperature even though
the engine has run long enough. • Thermostat
• Leakage from sealing portion of thermostat
• Engine coolant temperature sensor
Vehicle specification Vehicle serial number
Procedure
2WD with ASCD Up to 327618
A
Between 327619 and 912536 B
From 912537 C
2WD with ICC Up to 327618
A
Between 327619 and 914347 B
From 914348 C
4WD with ASCD Up to 327618
A
Between 327619 and 913067 B
From 913068 C
4WD with ICC Up to 327618
A
Between 327619 and 912422 B
From 912423 C
Revision: March 2010 2008 QX56

P0128 THERMOSTAT FUNCTIONEC-139
< COMPONENT DIAGNOSIS > [VK56DE]
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If “COOLAN TEMP/S” increases to more than 71°
C (160°F) within 30 minutes, turn ignition switch
OFF because the test result will be OK.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to EC-140, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PROCEDURE B
With CONSULT-III
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
•For best results, perform at ambient temperature of –10 °C (14° F) or higher.
• For best results, perform at engine coolant temperature of –10 °C (14° F) to 52 °C (126° F).
• Before performing the following pro cedure, do not fill with the fuel.
1. Turn A/C switch OFF.
2. Turn blower fan switch OFF.
3. Turn ignition switch ON.
4. Select “COOLAN TEMP/S” in “DAT A MONITOR” mode with CONSULT-III.
5. Check the indication of “COOLAN TEMP/S”. If it is below 52 °C (126 °F), go to following step.
If it is above 52 °C (126° F), cool down the engine to less than 52° C (126°F). Then go to next steps.
6. Start engine and wait at idle for at least 30 minutes. If “COOLAN TEMP/S” increases to more than 71° C (160°F) within 30 minutes, turn ignition switch
OFF because the test result will be OK.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to EC-140, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PROCEDURE C
With CONSULT-III
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
•For best results, perform at ambient temperature of –10 °C (14° F) or higher.
• For best results, perform at engine coolant temperature of –10 °C (14° F) to 56 °C (133° F).
• Before performing the following pro cedure, do not fill with the fuel.
1. Turn A/C switch OFF.
2. Turn blower fan switch OFF.
3. Turn ignition switch ON.
4. Select “COOLAN TEMP/S” in “DAT A MONITOR” mode with CONSULT-III.
5. Check the indication of “COOLAN TEMP/S”. If it is below 56 °C (133 °F), go to following step.
If it is above 56 °C (133° F), cool down the engine to less than 56° C (133°F). Then go to next steps.
6. Start engine and wait at idle for at least 30 minutes. If “COOLAN TEMP/S” increases to more than 75° C (167°F) within 30 minutes, turn ignition switch
OFF because the test result will be OK.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to EC-140, "
Diagnosis Procedure".
Revision: March 2010 2008 QX56

EC-140
< COMPONENT DIAGNOSIS >[VK56DE]
P0128 THERMOSTAT FUNCTION
With GST
Follow the procedure “With CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001449654
1.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-140, "
Component Inspection".
OK or NG
OK >> GO TO 2.
NG >> Replace engine coolant temperature sensor.
2.CHECK THERMOSTAT
Refer to CO-22, "
Removal and Installation".
OK or NG
OK >> INSPECTION END
NG >> Replace thermostat.
Component InspectionINFOID:0000000001449655
ENGINE COOLANT TEMPERATURE SENSOR
1. Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.

2. If NG, replace engine coolant temperature sensor.
PBIB2005E
Engine coolant temperature °C ( °F) Resistance kΩ
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
SEF012P
Revision: March 2010 2008 QX56

P0130, P0150 A/F SENSOR 1EC-141
< COMPONENT DIAGNOSIS > [VK56DE]
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P0130, P0150 A/F SENSOR 1
Component DescriptionINFOID:0000000001351457
The air fuel ratio (A/F) sensor 1 is a planar one-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is composed an elec-
trode layer, which transports ions. It has a heater in the element.
The sensor is capable of precise m
easurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range.
The exhaust gas components diffuse through the diffusion layer at
the sensor cell. An electrode layer is applied voltage, and this current
relative oxygen density in lean. Also this current relative hydrocar-
bon density in rich.
Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this
electrode layer of current. In addition, a heater is integrated in the
sensor to ensure the required operating temperature of about 800 °C
(1,472 °F).
On Board Diagnosis LogicINFOID:0000000001351459
To judge the malfunction, the diagnosis checks that the A/F signal computed by ECM from the A/F sensor 1
signal fluctuates according to fuel feedback control.
DTC Confirmation ProcedureINFOID:0000000001351460
Perform PROCEDURE FOR MALFUNCTION A first.
If the DTC cannot be confirmed, perform PROCEDURE FOR MALFUNCTION B.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.
PROCEDURE FOR MALFUNCTION A
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Let engine idle for 2 minutes.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-142, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PBIB3353E
PBIB3354E
DTC No. Trouble diagnosis name DTC detecting conditionPossible Cause
P0130
0130
(Bank 1) Air fuel ratio (A/F) sensor 1
circuit A)
The A/F signal computed by ECM from the A/F
sensor 1 signal is constantly in the range other
than approx. 2.2V.
• Harness or connectors
(The A/F sensor 1 circuit is open
or shorted.)
• Air fuel ratio (A/F) sensor 1
P0150
0150
(Bank 2) B)
The A/F signal computed by ECM from the A/F
sensor 1 signal is constantly approx. 2.2V.
Revision: March 2010
2008 QX56

EC-142
< COMPONENT DIAGNOSIS >[VK56DE]
P0130, P0150 A/F SENSOR 1
PROCEDURE FOR MALFUNCTION B
CAUTION:
Always drive vehicle at a safe speed.
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Select “A/F SEN1 (B1)” or “A/F SEN1 (B
2)” in “DATA MONITOR” mode with CONSULT-III.
3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
If the indication is constantly approx . 2.2V and does not fluctuates, go to EC-142, "
Diagnosis Procedure".
If the indication fluctuates around 2.2V, go to next step.
4. Select “A/F SEN1 (B1) P1276” (for DTC P0130) or “A/F SEN1 (B2) P1286” (for DTC P0150) of “A/F
SEN1” in “DTC WORK SUPPORT” mode with CONSULT-III.
5. Touch “START”.
6. When the following conditions are met, “TESTING” will be displayed on the CONSULT-III screen.
If “TESTING” is not displayed after 20 seconds, retry from step 2.
7. Release accelerator pedal fully. NOTE:
Never apply brake during releasing the accelerator pedal.
8. Make sure that “TESTING” changes to “COMPLETED”. If “TESTING” changed to “OUT OF CONDITION”, retry from step 6.
9. Make sure that “OK” is display ed after touching “SELF-DIAG RESULT”.
If “NG” is displayed, go to EC-142, "
Diagnosis Procedure".
Overall Function CheckINFOID:0000000001351461
PROCEDURE FOR MALFUNCTION B
Use this procedure to check the overall function of the A/F sensor 1 circuit. During this check, a 1st trip DTC
might not be confirmed.
With GST
1. Start engine and warm it up to normal operating temperature.
2. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in the suitable gear position.
3. Set shift lever to D position, then release the acce lerator pedal fully until the vehicle speed decreases to
50 km/h (30 MPH).
NOTE:
Never apply brake during releasing the accelerator pedal.
4. Repeat steps 2 and 3 for five times.
5. Stop the vehicle and turn ignition switch OFF.
6. Wait at least 10 seconds and restart engine.
7. Repeat steps 2 and 3 for five times.
8. Stop the vehicle and connect GST to the vehicle.
9. Make sure that no 1st trip DTC is displayed.
If the 1st trip DTC is displayed, go to EC-142, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000001351463
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
ENG SPEED 850 - 3,200 rpm
VHCL SPEED SE More than 64 km/h (40 MPH)
B/FUEL SCHDL 1.0 - 8.0 msec
Shift lever D position
Revision: March 2010 2008 QX56

P0131, P0151 A/F SENSOR 1EC-145
< COMPONENT DIAGNOSIS > [VK56DE]
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P0131, P0151 A/F SENSOR 1
Component DescriptionINFOID:0000000001351465
The air fuel ratio (A/F) sensor 1 is a planar one-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is composed an elec-
trode layer, which transports ions. It has a heater in the element.
The sensor is capable of precise m
easurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range.
The exhaust gas components diffuse through the diffusion layer at
the sensor cell. An electrode layer is applied voltage, and this current
relative oxygen density in lean. Also this current relative hydrocar-
bon density in rich.
Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this
electrode layer of current. In addition, a heater is integrated in the
sensor to ensure the required operating temperature of about 800 °C
(1,472 °F).
On Board Diagnosis LogicINFOID:0000000001351467
To judge the malfunction, the diagnosis checks that the A/F signal computed by ECM from the A/F sensor 1
signal is not inordinately low.
DTC Confirmation ProcedureINFOID:0000000001351468
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 10.5V at idle.
WITH CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Select “A/F SEN1 (B1)” or “A/F SEN1 (B2)” in “DATA MONITOR” mode with CONSULT-III.
3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication. If the indication is constantly approx. 0V, go to EC-146, "
Diagnosis Procedure".
If the indication is not constantly approx. 0V, go to next step.
4. Turn ignition switch OFF, wait at least 10 seconds and then restart engine.
5. Drive and accelerate vehicle to more than 40 km/h (25 MPH) within 20 seconds after restarting engine.
6. Maintain the following conditions for about 20 consecutive seconds.
PBIB3353E
PBIB3354E
DTC No. Trouble diagnosis name DTC detecting conditionPossible Cause
P0131
0131
(Bank 1) Air fuel ratio (A/F) sensor 1
circuit low voltage • The A/F signal computed by ECM from the A/
F sensor 1 signal is constantly approx. 0V. • Harness or connectors
(The A/F sensor 1 circuit is open or
shorted.)
• Air fuel ratio (A/F) sensor 1
P0151
0151
(Bank 2)
Revision: March 2010
2008 QX56

EC-146
< COMPONENT DIAGNOSIS >[VK56DE]
P0131, P0151 A/F SENSOR 1
NOTE:
•
Keep the accelerator pedal as steady as possible during the cruising.
• If this procedure is not completed within 1 minute af ter restarting engine at step 4, return to step
4.
7. Check 1st trip DTC.
8. If 1st trip DTC is displayed, go to EC-146, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001351470
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-86, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect A/F sensor 1 harness connector.
2. Turn ignition switch ON.
ENG SPEED 1,000 - 3,200 rpm
VHCL SPEED SE More than 40 km/h (25 MPH)
B/FUEL SCHDL 1.5 - 9.0 msec
Gear position Suitable position
BBIA0354E
BBIA0376E
Revision: March 2010 2008 QX56