System -- Basic Engine Control System

2019 Infiniti Q70 3.7 Luxe, AWDSECTION 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

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

System Description

Air

Positive crankcase ventilation system

3

3

4

4

4

4

4

4

4

4

1

Inspection 

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 , DTC Logic

Engine coolant temperature sensor circuit

3

3

3

DTC Logic , DTC Logic

Air fuel ratio (A/F) sensor 1 circuit

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

1

3

DTC Logic , DTC Logic

Crankshaft position sensor (POS) circuit

2

2

DTC Logic

Camshaft position sensor (PHASE) circuit

3

2

DTC Logic

Vehicle speed signal circuit

2

3

3

3

DTC Logic

Power steering pressure sensor circuit

2

3

3

DTC Logic

ECM

2

2

3

3

3

3

3

3

3

3

3

DTC Logic , DTC Logic

Intake valve timing control solenoid valve circuit

3

2

1

3

2

2

3

3

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 actuator 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

Work Flow

ABS actuator and electric unit (control unit)

4

Work Flow

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

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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.