Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSINFINITI2013QX56 RWDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - INTRODUCTIONDTC/CIRCUIT DIAGNOSISTROUBLE DIAGNOSIS - SPECIFICATION VALUEDIAGNOSIS PROCEDUREDETAILED PROCEDURE

2013 Infiniti QX56 RWD

Detailed Procedure

2013 Infiniti QX56 RWDSECTION Detailed Procedure

CHECK "A/F ALPHA-B1" AND "A/F ALPHA-B2"
With CONSULT
1. Start engine.
2. Check that the testing conditions are met. Refer to "COMPONENT FUNCTION CHECK ".
3. 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.
  NOTE: Check "A/F ALPHA-B1" and "A/F ALPHA-B2" for approximately 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.
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.
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.
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.
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 detected after changing engine oil or changing driving conditions.
  
  INSPECTION END
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.
DETECT MALFUNCTIONING PART
Check the following below.
- Ignition coil and its circuit (Refer to "COMPONENT FUNCTION CHECK ".)
- Fuel injector and its circuit (Refer to "COMPONENT FUNCTION CHECK ".)
- Intake air leakage
- Low compression pressure (Refer to "INSPECTION ".)
  Is the inspection result normal?
  
  YES: Replace fuel injector and then GO TO 8.
  
  NO: Repair or replace malfunctioning part and then GO TO 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 "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: GO TO 9.
CHECK A/F SENSOR 1 FUNCTION
Perform all DTC CONFIRMATION PROCEDURE related with A/F sensor 1.
- For DTC P0130, P0150, refer to "DTC LOGIC ".
- For DTC P0131, P0151, refer to "DTC LOGIC ".
- For DTC P0132, P0152, refer to "DTC LOGIC ".
- For DTC P0133, P0153, refer to "DTC LOGIC ".
- For DTC P2096, P2097, P2098, P2099 refer to "DTC LOGIC ".
  Are any DTCs detected?
  
  YES: GO TO 10.
  
  NO: GO TO 12.
CHECK A/F SENSOR 1 CIRCUIT
Perform Diagnosis Procedure according to corresponding DTC.

GO TO 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 "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: GO TO 12.
DISCONNECT AND RECONNECT 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 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 "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 "SYMPTOM TABLE ".
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: INSPECTION END

NO-1: More than the SP value: GO TO 15.

NO-2: Less than the SP value: GO TO 22.
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, alternator, 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.
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.
CHECK "A/F ALPHA-B1", "A/F ALPHA-B2" AND "B/FUEL SCHDL"
Select "A/F ALPHA-B1", "A/F ALPHA-B2" and "B/FUEL 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.
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.
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 "DIAGNOSIS PROCEDURE ". Then GO TO 26.
  
  NO: GO TO 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 malfunctioning mass air flow sensor, and then GO TO 26.
REPLACE ECM
1. Replace ECM.
2. Perform "WORK PROCEDURE ".
GO TO 26.
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.
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: INSPECTION END

NO: Less than the SP value: GO TO 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.
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, stuck 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.
CHECK "A/F ALPHA-B1", "A/F ALPHA-B2" AND "B/FUEL SCHDL"
Select "A/F ALPHA-B1", "A/F ALPHA-B2" and "B/FUEL 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 "SYMPTOM TABLE ".
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 "SYMPTOM TABLE ".

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.