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.
2024 Infiniti QX55 EssentialFACTORY OEM SERVICE PROCEDURE
Symptom Table
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 | ||||
| Direct fuel injector circuit | 1 | 1 | 2 | 3 | 2 | 2 | 2 | 2 | Diagnosis Procedure | ||||||
| Port fuel injector circuit | 1 | 1 | 2 | 3 | 2 | 2 | 2 | 2 | Diagnosis Procedure | ||||||
| Evaporative emission system | 3 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | Inspection | ||||
| Fuel rail pressure sensor circuit | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | DTC Description | ||||||
| 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 | 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 Description , DTC Description | |||
| Intake manifold runner control valve circuit | 4 | 4 | DTC Description | ||||||||||||
| 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 | |||||
| Main power supply and ground circuit | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | Diagnosis Procedure | ||||||
| Mass air flow sensor circuit | 2 | ||||||||||||||
| Engine coolant temperature sensor circuit | 3 | 3 | 3 | DTC Description | |||||||||||
| Air fuel ratio (A/F) sensor 1 circuit | DTC Description , DTC Description , DTC Description | ||||||||||||||
| Throttle position sensor circuit | 2 | 2 | DTC Description , DTC Description , DTC Description , DTC Description , DTC Description | ||||||||||||
| Accelerator pedal position sensor circuit | 3 | 2 | 1 | DTC Description , DTC Description , DTC Description | |||||||||||
| Heated oxygen sensor 2 circuit | 6 | 6 | 6 | 6 | 5 | ||||||||||
| Knock sensor circuit | 2 | 3 | DTC Description | ||||||||||||
| Engine oil temperature sensor circuit | 4 | 2 | 3 | DTC Description | |||||||||||
| Engine oil pressure sensor circuit | 4 | 4 | 3 | 3 | 3 | 3 | |||||||||
| Crankshaft position sensor circuit | 2 | 2 | DTC Description | ||||||||||||
| Intake camshaft position sensor (PHASE) circuit | 3 | 2 | DTC Description | ||||||||||||
| Turbocharger boost sensor circuit | 3 | 3 | |||||||||||||
| Manifold absolute pressure sensor circuit | 2 | ||||||||||||||
| Vehicle speed signal circuit | 2 | 3 | 3 | 3 | DTC Description | ||||||||||
| ECM | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | DTC Description | |||
| Electric Intake valve timing control module circuit | 3 | 3 | 3 | ||||||||||||
| Exhaust valve timing control solenoid valve circuit | 3 | 2 | 1 | 3 | 2 | 2 | 3 | 3 | DTC Description ,DTC Description | ||||||
| Electric Intake valve timing control actuator circuit | 3 | ||||||||||||||
| Exhaust camshaft position sensor circuit | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | DTC Description | ||||||
| Transmission range switch | 3 | 3 | 3 | 3 | 3 | DTC Description | |||||||||
| Intake manifold runner control valve motor circuit | 5 | 4 | 4 | 2 | 4 | 4 | 4 | 4 | |||||||
| Intake manifold runner control valve position sensor circuit | |||||||||||||||
| Turbocharger bypass control valve circuit | 3 | 3 | |||||||||||||
| Electric wastegate valve circuit | 1 | ||||||||||||||
| Electric recircuration valve circuit | 1 | ||||||||||||||
| Refrigerant pressure sensor circuit | 2 | 3 | 3 | 4 | Component Function Check | ||||||||||
| Cooling fan control module circuit | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | |||||
| Battery current sensor circuit | 4 | 5 | 5 | ||||||||||||
| 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 | |||||||||||||
| VCR System | 5 | 1 | 2 | 3 | 4 | 6 | |||||||||
1 - 6: The numbers refer to the order of inspection.(continued on next table)
SYSTEM - ENGINE MECHANICAL and OTHER
| 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 tank | 5 | 5 | Inspection | |||||||||||
| Fuel piping | 5 | 5 | 5 | 5 | 5 | 5 | Inspection | ||||||||
| Vapor lock | - | ||||||||||||||
| Valve deposit | 5 | 5 | 5 | 5 | 5 | 5 | 5 | - | |||||||
| Poor fuel (Heavy weight gasoline, Low octane) | - | ||||||||||||||
| Air | Air duct | 5 | 5 | 5 | 5 | 5 | 5 | Inspection | |||||||
| Air cleaner | Inspection | ||||||||||||||
| Air leakage from air duct (Mass air flow sensor - electric throttle control actuator) | 5 | 5 | 5 | 5 | Inspection | ||||||||||
| Electric throttle control actuator | Exploded View | ||||||||||||||
| Air leakage from intake manifold/Collector/Gasket | - | ||||||||||||||
| Cranking | Battery | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Work Flow | |||||
| Generator circuit | Work Flow (With 165- DSS-5000P) , Work Flow (Without 165- DSS-5000P) | ||||||||||||||
| Starter circuit | 3 | Work Flow (With 165- DSS-5000P) , Work Flow (Without 165- DSS-5000P) | |||||||||||||
| Signal plate | 6 | Exploded View | |||||||||||||
| Transmission range switch | 4 | Component Inspection | |||||||||||||
| Engine | Cylinder head | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | Inspection | |||||
| Cylinder head gasket | 4 | 3 | |||||||||||||
| Cylinder block | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 4 | Serviced as an assembly | |||||
| Piston | |||||||||||||||
| Piston ring | |||||||||||||||
| Connecting rod | |||||||||||||||
| Bearing | |||||||||||||||
| Crankshaft | |||||||||||||||
| Valve mechanism | Timing chain | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | Inspection | |||||
| Camshaft | Inspection | ||||||||||||||
| Intake valve timing control | Inspection | ||||||||||||||
| Exhaust valve timing control | Inspection | ||||||||||||||
| Intake valve | 3 | Inspection | |||||||||||||
| Exhaust valve | |||||||||||||||
| Exhaust | Exhaust manifold/Tube/Muffler/Gasket | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | Inspection ,Inspection | |||||
| Three way catalyst | |||||||||||||||
| Lubrication | Oil pan/Oil strainer/Oil pump/Oil filter/Oil gallery/Oil cooler | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | Inspection ,Inspection ,Inspection | |||||
| Oil level (Low)/Filthy oil | Inspection | ||||||||||||||
| Variable displacement oil pump | 5 | 5 | 4 | 4 | |||||||||||
| Cooling | Radiator/Hose/Radiator filler cap | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | Inspection ,Inspection | ||||
| Multi-way control valve | 5 | Component Inspection (Multi-way Control Valve) | |||||||||||||
| Water pump | Inspection | ||||||||||||||
| Water gallery | Engine Cooling System Schematic | ||||||||||||||
| Cooling fan | 5 | Exploded View | |||||||||||||
| Coolant level (Low)/Contaminated coolant | Inspection | ||||||||||||||
1 - 6: The numbers refer to the order of inspection.
Factory Service Tools
Use the Manual With the Right Hardware
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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.