Symptom Chart

Symptom (general)	Symptom (specific)	Possible causes	Action
Non-Start	Engine does not crank	Security system /Immobilizer engaged ECM relay Battery Starting system Harness Engine seized	Check that the security system is disarmed. Check the ECM relay operation. For battery information and starting system tests, refer to the relevant workshop information section. Check that the engine turns by hand.
	Engine cranks, but does not fire	Low/Contaminated fuel Ignition system Fuel system Crankshaft position (CKP) sensor Harness ECM fault	Check the fuel level and condition. For ignition system tests and fuel system tests, refer to the relevant workshop information section. For CKP and harness tests refer to the guided diagnostic routine on the approved diagnostic system. Refer to the warranty policy and procedures information if an ECM is suspect.
	Engine cranks and fires, but will not start	Evaporative emissions purge valve Fuel system Spark plugs Ignition coil failure(s) Harness	For purge valve tests, fuel system tests and ignition system tests, refer to the relevant workshop information section.
Difficult to start	Difficult to start cold	Check coolant anti-freeze content Battery Crankshaft position (CKP) sensor Exhaust gas recirculation (EGR) valve stuck ope Fuel system Evaporative emissions purge valve	For battery information, refer to the relevant workshop information section. For CKP and harness tests refer to the guided diagnostic routine on the approved diagnostic system. For EGR system tests, fuel system tests and purge valve tests, refer to the relevant workshop information section.
	Difficult to start hot	Injector leak Fuel system Fuel temperature sensor Intake air temperature (IAT) sensor Mass air flow (MAF) sensor Evaporative emissions purge valve Ignition system	For injector and fuel system tests, refer to the relevant workshop information section. For fuel temperature sensor, IAT sensor, MAF sensor and purge valve tests refer to the guided diagnostic routines on the approved diagnostic system. For ignition system tests, refer to the relevant workshop information section
	Difficult to start after hot soak (vehicle standing after engine has reached operating temperature)	Injector leak Fuel system Fuel temperature sensor IAT sensor MAF sensor Evaporative emissions purge valve Ignition system	For injector and fuel system tests, refer to the relevant workshop information section. For fuel temperature sensor, IAT sensor, MAF sensor and purge valve tests refer to the guided diagnostic routines on the approved diagnostic system. For ignition system tests, refer to the relevant workshop information section.
	Engine cranks too fast/slow	Compressions high/low Battery Starting system	Check compressions. For battery information and starting system tests, refer to the relevant workshop information section.
Engine stalls	Engine stalls soon after start	Breather system disconnected/restricted ECM relay MAF sensor Ignition system Air filter restricted Air leakage Fuel lines	Check the engine breather system. Check the ECM relay operation. For MAF sensor tests refer to the guided diagnostic routines on the approved diagnostic system. For ignition system test, air intake information and fuel line information, refer to the relevant workshop manual section
	Engine stalls on overrun	ECM relay Throttle position (TP) sensors	Check the ECM relay operation. For TP sensor tests refer to the guided diagnostic routines on the approved diagnostic system.
	Engine stalls at steady speed	ECM relay CKP sensor TP sensors	Check the ECM relay operation. For CKP sensor and TP sensor tests refer to the guided diagnostic routines on the approved diagnostic system.
	Engine stalls with speed control enabled	ECM relay	Check the ECM relay operation.
	Engine stalls when maneuvering	ECM relay TP sensors Additional engine loads (PAS, air conditioning, etc) Transmission malfunction CAN malfunction	Check the ECM relay operation. For TP sensor tests refer to the guided diagnostic routines on the approved diagnostic system. For accessory drive and transmission information, refer to the relevant workshop manual section. Check for CAN fault codes.
Poor driveability	Engine hesitates/poor acceleration	Fuel pump Fuel lines Injector leak Fuel pressure Air leakage TP sensors Throttle motor Ignition system EGR valve stuck HO2 sensors Transmission malfunction Restricted pedal travel (carpet, etc) Accelerator pedal position (APP) sensor	For fuel pump and fuel line information, injector tests and intake system checks, refer to the relevant workshop manual section. For TP sensor and throttle motor tests refer to the guided diagnostic routines on the approved diagnostic system. For ignition system tests and EGR tests, refer to the relevant workshop manual section. Check for DTCs relating to HO2 sensors, refer to the DTC index. For transmission information, refer to the relevant workshop manual section. Check the accelerator pedal travel. For APP sensor tests refer to the guided diagnostic routines on the approved diagnostic system.
	Engine backfires	Fuel pump Fuel lines Air leakage MAF sensor HO2 sensors Ignition system Sticking variable camshaft timing (VCT) hub APP sensor	For fuel pump and fuel line information and intake system, refer to the relevant workshop manual section. For MAF sensor tests refer to the guided diagnostic routines on the approved diagnostic system. Check for DTCs relating to HO2 sensors, refer to the DTC index. For ignition system tests, refer to the relevant workshop manual section. For VCT and APP sensor tests refer to the guided diagnostic routines on the approved diagnostic system.
	Engine surges	Fuel pump Fuel lines MAF sensor Harness TP sensors Throttle motor Ignition system	For fuel pump and fuel line information, refer to the relevant workshop manual section. For MAF sensor, TP sensor and throttle motor tests refer to the guided diagnostic routines on the approved diagnostic system. For ignition system tests, refer to the relevant workshop manual section.
	Engine detonates/knocks	Knock sensor (KS)/circuit malfunction Fuel pump Fuel lines Fuel quality MAF sensor HO2 sensors Air leakage Sticking VCT hub BARO sensor malfunction (internal ECM fault)	For KS circuit tests refer to the guided diagnostic routines on the approved diagnostic system. For fuel pump and fuel line information, refer to the relevant workshop manual section. For MAF sensor tests refer to the guided diagnostic routine on the approved diagnostic system. Check for DTCs relating to HO2 sensors, refer to the DTC index. For intake system, refer to the relevant workshop manual section. For VCT tests refer to the guided diagnostic routines on the approved diagnostic system. Refer to the warranty policy and procedures manual if an ECM is suspect.
	No throttle response	APP sensor malfunction TP sensors Throttle motor	For APP sensor, TP sensor and throttle motor tests refer to the guided diagnostic routines on the approved diagnostic system.
	Speed control inhibited or disabled	Default mode enabled Speed control switch(es) TP sensors CAN fault	Check message center for default message. For speed control switch information, refer to the relevant workshop manual section. For TP sensor tests refer to the guided diagnostic routine on the approved diagnostic system. Check for CAN fault codes.
Poor throttle response		APP sensor malfunction TP sensors ECT sensor MAF sensor Transmission malfunction Traction control event Air leakage Breather system disconnected/restricted	For APP sensor, TP sensor, ECT sensor and MAF sensor tests refer to the guided diagnostic routines on the approved diagnostic system. For transmission information, intake system checks and breather system checks, refer to the relevant workshop manual section.
Engine defaults, warning lamp and messages. Refer to the owner handbook	TP sensors MAF sensor ECT sensor Harness	For TP sensor, MAF sensor and ECT sensor tests refer to the guided diagnostic routines on the approved diagnostic system.