Symptom Chart: Notes

Symptom	Possible Causes	Action
Engine cranks, but does not fire	Engine breather system disconnected/restricted Ignition system Fuel system Electronic engine control	Ensure the engine breather system is free from restriction and is correctly installed Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine cranks and fires, but will not start	Evaporative emissions purge valve Fuel pump Spark plugs HT short to ground (tracking) check rubber boots for cracks/damage Ignition system	Check for evaporative emissions, fuel system and ignition system related DTCs and refer to the relevant DTC Index
Difficult cold start	Engine coolant level/anti-freeze content Battery Electronic engine controls Fuel pump Purge valve	Check the engine coolant level and condition Ensure the battery is in a fully charged and serviceable condition Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Difficult hot start	Injector leak Electronic engine control Purge valve Fuel pump Ignition system	Check for injector leak, install new injector as required Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Difficult to start after hot soak (vehicle standing, engine off, after engine has reached operating temperature)	Injector leak Electronic engine control Purge valve Fuel pump Ignition system	Check for injector leak, install new injector as required Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine stalls soon after start	Breather system disconnected/restricted Engine Control Module (ECM) relay Electronic engine control Ignition system Air intake system restricted Air leakage Fuel lines	Ensure the engine breather system is free from restriction and is correctly installed Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index Check for blockage in air filter and air intake system Check for air leakage in air intake system
Engine hesitates/poor acceleration	Fuel pressure, fuel pump, fuel lines Injector leak Air leakage Electronic engine control Throttle motor Restricted accelerator pedal travel (carpet, etc) Ignition system Transmission malfunction	Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index Check for injector leak, install new injector as required Check for air leakage in air intake system Ensure accelerator pedal is free from restriction Using the manufacturer approved diagnostic system, check the Transmission Control Module (TCM) for related DTCs and refer to the relevant DTC index
Engine backfires	Fuel pump/lines Air leakage Electronic engine controls Ignition system Sticking variable camshaft timing (VCT) hub	Check for fuel system failures Check for air leakage in intake air system Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine surges	Fuel pump/lines Electronic engine controls Throttle motor Ignition system	Check for fuel system failures Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine detonates/knocks	Fuel pump/lines Air leakage Electronic engine controls Sticking Variable Camshaft Timing (VCT) hub	Check for fuel system failures Check for air leakage in intake air system Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
No throttle response	Electronic engine controls Throttle motor	Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Poor throttle response	Breather system disconnected/restricted Electronic engine controls Transmission malfunction Traction control event Air leakage	Ensure the engine breather system is free from restriction and is correctly installed Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM), Transmission Control Module (TCM), and Anti-lock Brake System control module (ABS) for related DTCs and refer to the relevant DTC index Check for air leakage in intake air system
Fuel gauge reading empty with fuel in the fuel tank	Active fuel level sensor circuit open circuit Passive fuel level sensor circuit open circuit Instrument cluster internal failure	Using the manufacturer approved diagnostic system, perform the guided diagnostic routine - Fuel Level Sensor Test