2018 Infiniti QX80 AWDFACTORY OEM SERVICE PROCEDURE

System -- Basic Engine Control System

SYMPTOM

Reference

HARD/NO START/RESTART (EXCP. HA)

ENGINE STALL

HESITATION/SURGING/FLAT SPOT

SPARK KNOCK/DETONATION

LACK OF POWER/POOR ACCELERATION

HIGH IDLE/LOW IDLE

ROUGH IDLE/HUNTING

IDLING VIBRATION

SLOW/NO RETURN TO IDLE

OVERHEATS/WATER TEMPERATURE HIGH

EXCESSIVE FUEL CONSUMPTION

EXCESSIVE OIL CONSUMPTION

BATTERY DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG

AH

AJ

AK

AL

AM

HA

Fuel

Low pressure fuel pump circuit

1

1

2

3

2

2

2

3

2

Component Function Check

Fuel pressure regulator system

3

3

4

4

4

4

4

4

4

4

Work Procedure

Fuel injector circuit

1

1

2

3

2

2

2

2

Component Function Check

Evaporative emission system

3

3

4

4

4

4

4

4

4

4

Component InspectionΒ 

FRP sensor circuit

1

1

2

2

2

2

2

2

DTC Logic

DTC Logic

High pressure fuel pump circuit

4

3

Component Function Check

Air

Positive crankcase ventilation system

3

3

4

4

4

4

4

4

4

4

1

Refer to POSITIVE CRANKCASE VENTILATION : PERIODIC MAINTENANCE .

Incorrect idle speed adjustment

1

1

1

1

1

Work Procedure

Electric throttle control actuator

1

1

2

3

3

2

2

2

2

2

2

DTC Logic

DTC Logic

Ignition

Incorrect ignition timing adjustment

3

3

1

1

1

1

1

1

Work Procedure

Ignition circuit

1

1

2

2

2

2

2

2

Component Function Check

Main power supply and ground circuit

2

2

3

3

3

3

3

2

3

Diagnosis Procedure

Mass air flow sensor circuit

1

1

2

2

2

2

2

2

DTC Logic

Engine coolant temperature sensor 1 circuit

3

3

3

DTC Logic

Air fuel ratio (A/F) sensor 1 circuit

DTC Logic

DTC Logic

DTC Logic

DTC Logic

DTC Logic

Throttle position sensor circuit

2

2

DTC Logic

DTC Logic

DTC Logic

DTC Logic

DTC Logic

Accelerator pedal position sensor circuit

3

2

1

DTC Logic

DTC Logic

DTC Logic

Knock sensor circuit

2

3

DTC Logic

Engine oil temperature sensor

4

2

3

DTC Logic

Engine oil pressure sensor

4

4

3

3

3

3

DTC Logic

Crankshaft position sensor circuit

2

2

DTC Logic

Camshaft position sensor circuit

3

2

DTC Logic

Vehicle speed signal circuit

2

3

3

3

Description

Power steering pressure sensor circuit

2

3

3

DTC Logic

ECM

2

2

3

3

3

3

3

3

3

3

3

-

Intake valve timing control solenoid valve circuit

3

2

1

3

2

2

3

3

DTC Logic

Exhaust valve timing control solenoid valve circuit

3

2

1

3

2

2

3

3

DTC Logic

DTC Logic

Exhaust valve timing control position sensor

5

5

5

5

5

5

5

5

DTC Logic

Exhaust gas temperature sensor

5

DTC Logic

DTC Logic

VVEL control module

3

4

4

3

DTC Logic

DTC Logic

VVEL actuator motor

3

4

4

3

DTC Logic

VVEL actuator motor relay

3

4

4

3

DTC Logic

VVEL control shaft position sensor

3

4

4

3

DTC Logic

PNP signal circuit

3

3

3

3

3

DTC Logic

Refrigerant pressure sensor circuit

2

3

3

4

Component Function Check

Electrical load signal circuit

3

Component Function Check

Air conditioner circuit

2

2

3

3

3

3

3

3

3

3

2

Diagnosis Chart By Symptom

ABS actuator and electric unit (control unit)

4

Work Flow

Battery current sensor

4

5

5

3

DTC Logic

DTC Logic

DTC Logic

Heated oxygen sensor 2

6

6

6

6

5

DTC Logic

DTC Logic

Component Inspection (HO2 sensor 2)

1 - 6: The numbers refer to the order of inspection.

(continued on next chart)

Factory Service Tools

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When to See a Mechanic

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

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

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