2011 INFINITI QX56 engine

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-161
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DTC/CIRCUIT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:0000000006217760
The specification (SP) value indicates the tolerance of
the value that is displayed in “SPEC” in “DATA MONI-
TOR” mode of CONSULT-III during normal operation of the Engine Control System. When the value in “SPEC”
in “DATA MONITOR” mode is within the SP value, t he Engine Control System is confirmed OK. When the
value in “SPEC” in “DATA MONITOR” mode is NOT wit hin the SP value, the Engine Control System may have
one or more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not illuminate
the MIL.
The SP value will be displayed for the following items:
 B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board correc- tion)
 A/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
 MAS A/F SE-B1/B2 (The signal voltage of the mass air flow sensor)
 IDLE FUEL PRES MAX/MIN (the signal voltage of the fuel rail pressure sensor)
Component Function CheckINFOID:0000000006217761
1.PRECONDITIONING
Check that all of the following conditions are satisfied.
TESTING CONDITION
 Vehicle driven distance: More than 5,000 km (3,107 miles)
 Barometric pressure: 98.3 - 104.3 kPa (0.983 - 1.043 bar, 1.003 - 1.064 kg/cm
2, 14.25 - 15.12 psi)
 Atmospheric temperature: 20 - 30 °C (68 - 86 °F)
 Engine coolant temperature: 75 - 95 °C (167 - 203 °F)
 Transmission: Warmed-up
- After the engine is warmed up to normal operating temperat ure, drive vehicle until “ATF TEMP 2” (A/T fluid
temperature sensor signal) indicates more than 60 °C (140 °F).
 Electrical load: Not applied
- Rear window defogger switch, air conditioner switch and li ghting switch are OFF. Steering wheel is straight
ahead.
 Engine speed: Idle
 Gear position: Neutral ( or parking)
>> GO TO 2.
2.PERFORM SPEC IN DATA MONITOR MODE
WITH CONSULT-III
NOTE:
Perform “SPEC” in “DATA MONITOR” mode in maximum scale display.
1. Perform EC-139, "
Work Procedure".
2. Select “B/FUEL SCHDL”, “A/F ALPHA-B1”, “A/F ALPHA-B2”, “MAS A/F SE-B1” in “SPEC” of “DATA
MONITOR” mode with CONSULT-III.
3. Check that monitor items are within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Proceed to EC-162, "
Diagnosis Procedure".
Revision: 2010 May2011 QX56

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-163
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DETAILED PROCEDURE
1.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
WITH CONSULT-III
1. Start engine.
2. Check that the testing conditions are met. Refer to EC-161, "
Component Function Check".
3. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
JMBIA0056GB
Revision: 2010 May2011 QX56

EC-164
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
NOTE:
Check “A/F ALPHA-B1” and “A/F ALPHA-B2” for approxim
ately 1 minute because they may fluctuate. It is
NG if the indication is out of the SP value even a little.
Is the measurement value within the SP value?
YES >> GO TO 14.
NO-1 >> Less than the SP value: GO TO 2.
NO-2 >> More than the SP value: GO TO 3.
2.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 4.
NO >> More than the SP value: GO TO 16.
3.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 6.
NO-1 >> More than the SP value: GO TO 6.
NO-2 >> Less than the SP value: GO TO 22.
4.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Stop the engine.
2. Disconnect PCV hose, and then plug it.
3. Start engine.
4. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “ SPEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> GO TO 5.
NO >> GO TO 6.
5.CHANGE ENGINE OIL
1. Stop the engine.
2. Change engine oil. NOTE:
This symptom may occur when a large amount of gasoline is mixed with engine oil because of driving
conditions (such as when engine oil temperature does not rise enough since a journey distance is too
short during winter). The symptom will not be detec ted after changing engine oil or changing driving con-
ditions.
>> INSPECTION END
6.PERFORM POWER BALANCE TEST
1. Perform “POWER BALANCE” in “ACTIVE TEST” mode.
2. Check that each cylinder produces a momentary engine speed drop.
Is the inspection result normal?
YES >> GO TO 9.
NO >> GO TO 7.
7.DETECT MALFUNCTIONING PART
Check the following below.
 Ignition coil and its circuit (Refer to EC-506, "
Component Function Check".)
 Fuel injector and its circuit (Refer to EC-498, "
Component Function Check".)
 Intake air leakage
 Low compression pressure (Refer to EM-16, "
Inspection".)
Is the inspection result normal?
Revision: 2010 May2011 QX56

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-165
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YES >> Replace fuel injector and then GO TO 8.
NO >> Repair or replace malfunctioning part and then GO TO 8.
8.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> GO TO 9.
9.CHECK A/F SENSOR 1 FUNCTION
Perform all DTC CONFIRMATION PROCEDURE related with A/F sensor 1.
 For DTC P0130, P0150, refer to EC-228, "
DTC Logic".
 For DTC P0131, P0151, refer to EC-232, "
DTC Logic".
 For DTC P0132, P0152, refer to EC-235, "
DTC Logic".
 For DTC P0133, P0153, refer to EC-238, "
DTC Logic".
 For DTC P2A00, P2A03, refer to EC-487, "
DTC Logic".
Are any DTCs detected?
YES >> GO TO 10.
NO >> GO TO 12.
10.CHECK A/F SENSOR 1 CIRCUIT
Perform Diagnosis Procedure according to corresponding DTC.
>> GO TO 11.
11 .CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> GO TO 12.
12.DISCONNECT AND RECONNECT ECM HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect ECM harness connector. Check pin term inal and connector for damage, and then reconnect it.
>> GO TO 13.
13.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Detect malfunctioning part according to EC-524, "
Symptom Table".
14.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check t hat the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO-1 >> More than the SP value: GO TO 15.
NO-2 >> Less than the SP value: GO TO 22.
15.DETECT MALFUNCTIONING PART
Revision: 2010 May2011 QX56

EC-166
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
1. Check for the cause of large engine friction. Refer to the following.
- Engine oil level is too high
- Engine oil viscosity
- Belt tension of power steering, alternat
or, A/C compressor, etc. is excessive
- Noise from engine
- Noise from transmission, etc.
2. Check for the cause of insufficient combustion. Refer to the following.
- Valve clearance malfunction
- Intake valve timing control function malfunction
- Camshaft sprocket installation malfunction, etc.
>> Repair or replace malfunctioning part, and then GO TO 27.
16.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.
 Crushed air ducts
 Malfunctioning seal of air cleaner element
 Uneven dirt of air cleaner element
 Improper specification of intake air system
Is the inspection result normal?
YES >> GO TO 18.
NO >> Repair or replace malfunctioning part, and then GO TO 17.
17.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2” AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2” and “B/FUE L SCHDL” in “SPEC” of “DATA MONITOR” mode, and
check that each indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> “B/FUEL SCHDL” is more, “A/F ALPHA-B1” and “A /F ALPHA-B2” are less than the SP value: GO
TO 18.
18.DISCONNECT AND RECONNECT MASS AIR FLOW SENSOR HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect mass air flow sensor harness connector. Check pin terminal and connector for damage and then reconnect it again.
>> GO TO 19.
19.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “ SPEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> Detect malfunctioning part of mass air flow sensor circuit and repair it. Refer to EC-201, "Diagno-
sis Procedure". Then GO TO 26.
NO >> GO TO 20.
20.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 21.
NO >> More than the SP value: Replace malfuncti oning mass air flow sensor, and then GO TO 26.
21.REPLACE ECM
1. Replace ECM.
2. Perform EC-143, "
Work Procedure".
Revision: 2010 May2011 QX56

P0011, P0021 IVT CONTROLEC-177
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P0011, P0021 IVT CONTROL
DTC LogicINFOID:0000000006217772
DTC DETECTION LOGIC
NOTE:
If DTC P0011 or P0021 is displayed with DTC P0075
or P0081, first perform the trouble diagnosis for
DTC P0075, P0081. Refer to EC-193, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE-I
WITH CONSULT-III
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to the normal operating temperature.
3. Maintain the following conditions for at least 6 consecutive seconds. Hold the accelerator pedal as steady as possible.
4. Let engine idle for 25 seconds.
5. Check 1st trip DTC. WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Go to EC-178, "Diagnosis Procedure"
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE-II
WITH CONSULT-III
1. Select “DATA MONITOR” mode with CONSULT-III.
2. Maintain the following conditions for at least 20 consecutive seconds.
DTC No. Trouble diagnosis
(Trouble diagnosis con- tent) Detecting condition Possible cause
P0011 INT/V TIM CONT-B1
[Intake valve timing control
performance (bank 1)]
There is a gap between angle of target
and phase-control angle degree.  Crankshaft position sensor
 Camshaft position sensor
 Intake valve timing control solenoid valve
 Accumulation of debris to the signal pick-up
portion of the camshaft
 Timing chain installation
 Foreign matter caught in the oil groove for in- take valve timing control
P0021
INT/V TIM CONT-B2
[Intake valve timing control
performance (bank 2)]
ENG SPEED Less than 2,000 rpm (A constant rotation is maintained.)
COOLAN TEMP/S More than 70
°C (158 °F)
Selector lever P or N position
ENG SPEED 1,500 - 3,175 rpm (A constant rotation is maintained.)
COOLAN TEMP/S More than 70 °C (158 °F)
Revision: 2010 May2011 QX56

EC-178
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P0011, P0021 IVT CONTROL
CAUTION:
Always drive at a safe speed.
3. Check 1st trip DTC.
WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Go to EC-178, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217773
1.CHECK OIL PRESSURE WARNING LAMP
1. Start engine.
2. Check that oil pressure warning lamp is not illuminated.
Is oil pressure warning lamp illuminated?
YES >> Go to LU-7, "Inspection".
NO >> GO TO 2.
2.CHECK INTAKE VALVE TIMING CONTROL SOLENOID VALVE
Refer to EC-179, "
Component Inspection (Intake Valve Timing Control Solenoid Valve)".
Is the inspection result normal?
YES >> GO TO 3.
NO >> Replace malfunctioning intake valve timing control solenoid valve. Refer to EM-61, "
Exploded
View".
3.CHECK CRANKSHAFT POSITION SENSOR
Refer to EC-301, "
Component Inspection (Crankshaft Position Sensor)".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace crankshaft position sensor. Refer to EM-106, "
Exploded View".
4.CHECK CAMSHAFT POSITION SENSOR
Refer to EC-306, "
Component Inspection (Camshaft Position Sensor)".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Replace malfunctioning camshaft position sensor. Refer to EM-106, "
Exploded View".
5.CHECK CAMSHAFT (INTAKE)
Check the following.
Selector lever 1st or 2nd position
Driving location uphill Driving vehicle uphill
(Increased engine load will help maintain the driving
conditions required for this test.)
PBIA8559J
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P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-181
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P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
DTC LogicINFOID:0000000006217775
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for at least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-181, "Diagnosis Procedure".
NG >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217776
1.CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect air fuel ratio (A /F) sensor 1 harness connector.
2. Turn ignition switch ON.
3. Check the voltage between A/F sensor 1 harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
DTC No. Trouble diagnosis
(Trouble diagnosis content) DTC detecting condition Possible cause
P0031 A/F SEN1 HTR (B1)
[A/F sensor 1 heater (bank
1) control circuit low] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
 A/F sensor 1 heater
P0032 A/F SEN1 HTR (B1)
[A/F sensor 1 heater (bank
1) control circuit high] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
 A/F sensor 1 heater
P0051 A/F SEN1 HTR (B2)
[A/F sensor 1 heater (bank
2) control circuit low] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
 A/F sensor 1 heater
P0052 A/F SEN1 HTR (B2)
[A/F sensor 1 heater (bank
2) control circuit high] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
 A/F sensor 1 heater
DTC A/F sensor 1
Ground Voltage
Bank Connector Terminal
P0031, P0032 1 F67 5 Ground Battery voltage
P0051, P0052 2 F68 5
Revision: 2010 May2011 QX56