Lexus NX: Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

  • Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
  • Inspect the fuses and relays related to this system before inspecting the suspected areas below.
SFI System:

Symptom

Suspected Area

Link

Engine does not crank (Does not start)

Immobiliser system

Hybrid control system

VC output circuit (ECM 5 V output)

No initial combustion (Does not start)

ECM power source circuit

VC output circuit (ECM 5 V output)

Crankshaft position sensor

Camshaft position sensor

Ignition system

EGR valve assembly

Fuel injector circuit

Valve timing

Fuel pump control circuit

ECM

Engine cranks normally but difficult to start

Engine coolant temperature sensor

Ignition system

Fuel injector assembly

Compression

Fuel injector circuit

EGR valve assembly

Intake system

Throttle body with motor assembly

ECM power source circuit

Fuel pump control circuit

Incomplete intermittent combustion occurs (Does not start)

Fuel line

-

Ignition system

Fuel injector assembly

EGR valve assembly

Crankshaft position sensor

Valve timing

Fuel pump control circuit

High engine speed

Throttle body with motor assembly

Engine coolant temperature sensor

PCV valve and hose

ECM power source circuit

Low engine speed (Poor idle)

Throttle body with motor assembly

Intake system

PCV valve and hose

Fuel pump control circuit

Rough idle

Rough Idling

Compression (engine mechanical)

Air fuel ratio sensor

Heated oxygen sensor

Mass air flow meter sub-assembly

Ignition system

Fuel line

-

Valve timing

Intake system

PCV valve and hose

Fuel pump control circuit

EGR valve assembly

Hunting (Poor idle)

PCV valve and hose

Mass air flow meter sub-assembly

Air fuel ratio sensor

Drive Start Control System

Hesitation/Poor acceleration (Poor driveability)

Fuel line

-

Valve timing

Mass air flow meter sub-assembly

Throttle body with motor assembly

Knock control sensor

Fuel pump control circuit

Brake override system

Drive Start Control System

Surging (Poor driveability)

Fuel line

-

Ignition system

Fuel injector assembly

Fuel pump control circuit

Engine stalls soon after starting

Mass air flow meter sub-assembly

Intake system

EGR valve assembly

Fuel line

-

Unable/difficult to refuel

Fuel system (canister, refueling valve, roll over valve, fuel tank, etc.)

-

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