2011 INFINITI QX56 Fuel

EC-164
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
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
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
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

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-167
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>> GO TO 26.
22.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 in air cleaner element
 Uneven dirt in air cleaner element
 Improper specification in intake air system
Is the inspection result normal?
YES >> GO TO 24.
NO >> Repair or replace malfunctioning part, and then GO TO 23.
23.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 >> Less than the SP value: GO TO 24.
24.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 25.
NO >> Less than the SP value: Replace malfunctioning mass air flow sensor, and then GO TO 27.
25.CHECK INTAKE SYSTEM
Check for the cause of air leakage after the mass air flow sensor. Refer to the following.
 Disconnection, looseness, and cracks in air duct
 Looseness of oil filler cap
 Disconnection of oil level gauge
 Open stuck, breakage, hose disconnection, or cracks in PCV valve
 Disconnection or cracks in EVAP purge hose, stuc k open EVAP canister purge volume control solenoid
valve
 Malfunctioning seal in rocker cover gasket
 Disconnection, looseness, or cracks in hoses, such as a vacuum hose, connecting to intake air system parts
 Malfunctioning seal in intake air system, etc.
>> GO TO 27.
26.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 >> Detect malfunctioning part according to EC-524, "
Symptom Table".
27.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and then check that the 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".
Revision: 2010 May2011 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-181
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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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

EC-182
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0031, P0032, P0051, P00
52 A/F SENSOR 1 HEATER
2.DETECT MALFUNCTIONING PART
Check the following.
 20 A fuse (No. 43)
 Harness for open or short between A/F sensor 1 and fuse
 Loose or poor connection for each connector and harness
>> Repair or replace harness or connectors.
3.CHECK A/F SENSOR 1 HEATER OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
4. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK A/F SENSOR 1 HEATER
Refer to EC-182, "
Component Inspection (A/F Sensor 1 Heater)".
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5.REPLACE A/F SENSOR 1
Replace malfunctioning A/F sensor 1. Refer to EM-40, "
Exploded View".
CAUTION:
 Discard any A/F sensor which has b een 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.
 Before installing new A/F sensor, clean exhau st system threads using Oxygen Sensor Thread
Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant
(commercial service tool).
>> INSPECTION END
6.CHECK INTERMITTENT INCIDENT
Perform GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (A/F Sensor 1 Heater)INFOID:0000000006217777
1.CHECK AIR FUEL RATIO (A/F) SENSOR 1
1. Turn ignition switch OFF.
2. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
3. Check resistance between A/F sensor 1 terminals as per the following.
DTC A/F sensor 1 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0031, P0032 1 F67 2 F11048
Existed
P0051, P0052 2 F68 2 53
Terminal Resistance
2 and 5 2.0 - 3.2 Ω [at 25 °C (77 °F)]
Revision: 2010 May2011 QX56

P0087, P0088, P0090 FRP CONTROL SYSTEM
EC-195
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P0087, P0088, P0090 FRP CONTROL SYSTEM
DTC LogicINFOID:0000000006217784
DTC DETECTION LOGIC
NOTE:

If DTC P0087 or P0090 is displayed with DTC P1197, first perform the trouble diagnosis for DTC
P1197.
 DTC P0087 or P0090 may be displayed when running out of gas.
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
1. Check that the fuel tank is 1/8 full of fuel.
2. Warm up the engine to the normal operating temperature and keep the engine speed at idle for 60 sec- onds.
NOTE:
Warm up the engine until “COOLAN TEMP/S” on “DATA MONITOR” of CONSULT-III reaches at least
70 °C (158 °F).
3. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-196, "Diagnosis Procedure".
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE-II
1. Cool the engine until the engine coolant temperature reaches 60 °C (140 °F) or less.
2. Start the engine and wait at least 60 seconds.
3. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-196, "Diagnosis Procedure".
NO >> INSPECTION END
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0087 High fuel pressure too low The following condition continues for 5
seconds or more after engine start (re-
gardless of water temperature): Target
fuel pressure
− Actual fuel pressure ≥
2.7 MPa (27 bar, 27.5 kg/cm
2, 392 psi)
 Harness or connectors(The fuel pump circuit is open or shorted.)
 Fuel system
P0088 high fuel pressure too high The following condition continues for 5
seconds or more after engine start (re-
gardless of water temperature):Actual
fuel pressure
− Target fuel pressure ≥
2.7 MPa (27 bar, 27.5 kg/cm
2, 392 psi)
P0090 High pressure fuel pump per-
formance Fuel rail pressure remains at 1.5 MPa
(15 bar, 15.3 kg/ cm
2, 217.5 psi) or less
for 3 seconds or more during engine rev.
Revision: 2010 May2011 QX56

EC-196
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0087, P0088, P009
0 FRP CONTROL SYSTEM
Diagnosis Procedure
INFOID:0000000006217785
1.CHECK LOW FUEL PRESSURE
WITH CONSULT-III
1. Start the engine.
2. Check “L/FUEL PRES SEN V” in “DAT A MONITOR” of “ECM” with CONSULT-III.
WITHOUT CONSULT-III
1. Start the engine.
2. Check low fuel pressure sensor signal voltage.
Is inspection result normal?
YES >> GO TO 2.
NO >> Check low fuel pressure system. Refer to EC-512, "
Diagnosis Procedure".
2.PERFORM THE HIGH PRESSURE FUEL PUMP COMPONENT INSPECTION
Perform the high pressure fuel pum p component inspection. Refer to EC-196, "
Component Inspection".
Is inspection result normal?
YES >> GO TO 3.
NO >> Replace the fuel pump.
3.CHECK FUEL LEAKAGE
1. Start the engine.
2. Visually check that the fuel pump, fuel rail, and fuel piping have no fuel leakage.
Is inspection result normal?
YES >> Check that the fuel syst em has no breakage, bend, and crush.
NO >> Repair or Replace the error-detected parts.
Component InspectionINFOID:0000000006217786
1.CHECK HIGH PRESSURE FUEL PUMP-I
1. Turn ignition switch OFF.
2. Disconnect high pressure fuel pump harness connector.
3. Check the resistance between high pressure fuel pump terminals as follows.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Replace high pressure fuel pump. Refer to EM-49, "
Removal and Installation".
Data monitor item Condition Va l u e
(Approx.)
L/FUEL PRES SEN V Engine speed: idle
3,000 –3,300 mV
Engine speed: 3,000 rpm (no load)
+ −Condition Va l u e
(Approx.)
Low fuel pressure sensor
Connector Terminal
F25 2 Ground Engine speed: idle
3.0 –3.3 V
Engine speed: 3,000 rpm (no load)
+ −
Condition Resistance
High pressure fuel pump
Te r m i n a l
1 2 Temperature °C ( °F) 20 – 30 (68 - 86) 9 - 11 Ω
Revision: 2010 May2011 QX56