2008 INFINITI QX56 Fuel

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-79
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>> GO TO 8.
8.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> GO TO 9.
9.PERFORM POWER BALANCE TEST
1. Perform “POWER BALANCE ” in “ACTIVE TEST” mode.
2. Make sure that the each cylinder produces a momentary engine speed drop.
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10.DETECT MALFUNCTIONING PART
1. Check the following.
- Ignition coil and its circuit (Refer to EC-411, "
Diagnosis Procedure" .)
- Fuel injector and its circuit (Refer to EC-399, "
Diagnosis Procedure" .)
- Intake air leakage
- Low compression pressure (Refer to EM-23, "
Checking Compression Pressure".)
2. If NG, repair or replace the malfunctioning part. If OK, replace fuel injector. (It may be caus ed by leakage from fuel injector or clogging.)
>> GO TO 11.
11 .CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> GO TO 12.
12.CHECK A/F SENSOR 1 FUNCTION
Perform all DTC Confirmation Procedure related with A/F sensor 1.
• For DTC P0130, P0150, refer to EC-141, "
DTC Confirmation Procedure" .
• For DTC P0131, P0151, refer to EC-145, "
DTC Confirmation Procedure" .
• For DTC P0132, P0132, refer to EC-149, "
DTC Confirmation Procedure" .
• For DTC P0133, P0153, refer to EC-153, "
DTC Confirmation Procedure" .
• For DTC P2A00, P2A03, refer to EC-385, "
DTC Confirmation Procedure" .
OK or NG
OK >> GO TO 15.
NG >> GO TO 13.
13.CHECK A/F SENSOR 1 CIRCUIT
Perform Diagnostic Procedure according to corresponding DTC.
>> GO TO 14.
14.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
Revision: March 2010 2008 QX56

EC-80
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
OK >>
INSPECTION END
NG >> GO TO 15.
15.DISCONNECT AND RECONNE CT ECM HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect ECM harness connector. Check pin terminal and connector for damage, and then reconnect it.
>> GO TO 16.
16.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F AL PHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the
each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> Detect malfunctioning part according to EC-481, "
Symptom Matrix Chart" .
17.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> INSPECTION END
NG (More than the SP value)>>GO TO 18.
NG (Less than the SP value)>>GO TO 25.
18.DETECT MALFUNCTIONING PART
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 30.
19.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
OK or NG
OK >> GO TO 21.
NG >> Repair or replace malfunctioning part, and then GO TO 20.
20.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”, AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2”, and “B/F UEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and
make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG (“B/FUEL SCHDL” is more, “A/F ALPHA-B1”, “A/F ALPHA-B2” are less than the SP value)>>GO TO 21.
21.DISCONNECT AND RECONNECT MASS AIR FLOW SENSOR HARNESS CONNECTOR
1. Stop the engine.
Revision: March 2010 2008 QX56

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-81
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2. Disconnect mass air flow sensor harness connecto
r. Check pin terminal and connector for damage and
then reconnect it again.
>> GO TO 22.
22.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> 1. Detect malfunctioning part of mass air flow sensor circuit and repair it. Refer to EC-113 .
2. GO TO 29.
NG >> GO TO 23.
23.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> GO TO 24.
NG (More than the SP value)>>Replace ma ss air flow sensor, and then GO TO 29.
24.REPLACE ECM
1. Replace ECM.
2. Perform initialization of IVIS(NATS) system and registration of all IVIS(NATS) ignition key IDs. Refer to SEC-8, "
ECM RE-COMMUNICATING FUNCTION : Special Repair Requirement".
3. Perform EC-17, "
VIN Registration" .
4. Perform EC-18, "
Accelerator Pedal Released Position Learning" .
5. Perform EC-18, "
Throttle Valve Closed Position Learning" .
6. Perform EC-18, "
Idle Air Volume Learning" .
>> GO TO 29.
25.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
OK or NG
OK >> GO TO 27.
NG >> Repair or replace malfunctioning part, and then GO TO 26.
26.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” m ode, and make sure that the indication is within the
SP value.
OK or NG
OK >> INSPECTION END
NG (Less than the SP value)>>GO TO 27.
27.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> GO TO 28.
NG (Less than the SP value)>>Replace ma ss air flow sensor, and then GO TO 30.
28.CHECK INTAKE SYSTEM
Check for the cause of air leak after the mass air flow sensor. Refer to the following.
Revision: March 2010 2008 QX56

EC-82
< COMPONENT DIAGNOSIS >[VK56DE]
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
• Disconnection, looseness, and cracks in air duct
• Looseness of oil filler cap
• Disconnection of oil level gauge
• Open stuck, breakage, hose disconnecti
on, or cracks of PCV valve
• Disconnection or cracks of EVAP purge hose, open stuc k of EVAP canister purge volume control solenoid
valve
• Malfunctioning seal of rocker cover gasket
• Disconnection, looseness, or cracks of hoses, such as vacuum hose, connecting to intake air system parts
• Malfunctioning seal of intake air system, etc.
>> GO TO 30.
29.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”, AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2”, and “B/F UEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and
make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> Detect malfunctioning part according to EC-481, "
Symptom Matrix Chart" .
30.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITO R” mode, and then make sure that the indication is
within the SP value.
OK or NG
OK >> INSPECTION END
NG >> Detect malfunctioning part according to EC-481, "
Symptom Matrix Chart" .
Revision: March 2010 2008 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-97
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P0031, P0032, P0051, P0052
A/F SENSOR 1 HEATER
DescriptionINFOID:0000000001351384
SYSTEM DESCRIPTION
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating
condition to keep the temperature of A/F sensor 1 element at the specified range.
On Board Diagnosis LogicINFOID:0000000001351378
DTC Confirmation ProcedureINFOID:0000000001351379
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, confi rm that battery voltage is between 10.5V and 16V at
idle.
WITH CONSULT-III
1. Start engine and let it idle for at least 10 seconds.
2. Check 1st trip DTC.
3. If 1st trip DTC is detected, go to EC-97, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001351381
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Sensor Input Signal to ECM ECM functionActuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS) Engine speed
Air fuel ratio (A/F) sensor 1
heater controlAir fuel ratio (A/F) sensor 1
heater
Mass air flow sensor Amount of intake air
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P0031
0031
(Bank 1) Air fuel ratio (A/F) sensor
1 heater control circuit low The current amperage in the air fuel ratio (A/F) sen-
sor 1 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the air fuel ratio (A/F) sensor 1 heater.) • Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
• A/F sensor 1 heater
P0051
0051
(Bank 2)
P0032
0032
(Bank 1)
Air fuel ratio (A/F) sensor
1 heater control circuit
high The current amperage in the air fuel ratio (A/F) sen-
sor 1 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the air fuel ratio (A/F) sensor 1 heater.) • Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
• A/F sensor 1 heater
P0052
0052
(Bank 2)
Revision: March 2010
2008 QX56

EC-98
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P0031, P0032, P0051, P00
52 A/F SENSOR 1 HEATER
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 air fuel ratio (A/F) sensor 1 harness connector.
2. Turn ignition switch ON.
3. Check voltage between A/F sensor 1 terminal 4 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors E5, F14
• IPDM E/R harness connector E119
• 15A fuse
• Harness for open or short between A/F sensor 1 and fuse
>> Repair or replace harness or connectors.
4.CHECK A/F SENSOR 1 HEATER OUTPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 2 (bank 1) or 24, 43 (bank 2) and A/F sensor 1 terminal
3.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
BBIA0354E
Voltage: Battery voltage
BBIA0376E
PBIB3308E
Continuity should exist.
Revision: March 2010 2008 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-99
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OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK A/F SENSOR 1 HEATER
Refer to EC-99, "
Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace malfunctioning air fuel ratio (A/F) sensor 1.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000001351382
AIR FUEL RATIO (A/F) SENSOR 1 HEATER
1. Check resistance between A/F sensor 1 terminals as follows.
2. If NG, replace air fuel ratio (A/F) sensor 1.
CAUTION:
• Discard any A/F 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.
• Before installing new A/F sensor, clean exhaust system threads using Heated Oxygen Sensor Thread Cleaner tool J-
43897-18 or J-43897-12 and approved anti-seize lubricant.
Terminal No. Resistance
3 and 4 1.98 - 2.66 Ω [at 25°C (77 °F)]
3 and 1, 2 ∞ Ω
(Continuity should not exist)
4 and 1, 2
PBIB3309E
Revision: March 2010 2008 QX56

P0102, P0103 MAF SENSOREC-113
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P0102, P0103 MAF SENSOR
Component DescriptionINFOID:0000000001351410
The mass air flow sensor is placed in
the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor c ontrols the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current s upplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
On Board Diagnosis LogicINFOID:0000000001351412
These self-diagnoses have the on e trip detection logic.
FA I L - S A F E M O D E
When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
DTC Confirmation ProcedureINFOID:0000000001351413
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.
PROCEDURE FOR DTC P0102
With CONSULT-III
1. Start engine and wait at least 5 seconds.
2. Check DTC.
3. If DTC is detected, go to EC-114, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PROCEDURE FOR DTC P0103
With CONSULT-III
1. Turn ignition switch ON.
2. Wait at least 5 seconds.
3. Check DTC.
4. If DTC is detected, go to EC-114, "
Diagnosis Procedure".
If DTC is not detected, go to next step.
5. Start engine and wait at least 5 seconds.
6. Check DTC.
7. If DTC is detected, go to EC-114, "
Diagnosis Procedure".
BBIA0355E
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P0102
0102 Mass air flow sensor circuit
low input An excessively low voltage from the sensor is
sent to ECM. • Harness or connectors
(The sensor circuit is open or shorted.)
• Intake air leaks
• Mass air flow sensor
P0103
0103 Mass air flow sensor circuit
high input An excessively high voltage from the sensor is
sent to ECM. • Harness or connectors
(The sensor circuit is open or shorted.)
• Mass air flow sensor
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.
Revision: March 2010 2008 QX56