DTC P0300-00: Random/Multiple Cylinder Misfire Detected; DTC P0300-27: Random/Multiple Cylinder Misfire Detected (Emission) Signal Rate of Change Above Threshold; DTC P0300-85: Random / Multiple Cylinder Misfire Detected (Over Temperature) Signal Above Allowable Range; DTC P0301-00: Cylinder 1 Misfire Detected; DTC P0302-00: Cylinder 2 Misfire Detected; DTC P0303-00: Cylinder 3 Misfire Detected; DTC P0304-00: Cylinder 4 Misfire Detected [11/2017 - ]: Description

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P0300-00	Random/Multiple Cylinder Misfire Detected	Simultaneous misfiring of several cylinders occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: P0300
P0300-27	Random/Multiple Cylinder Misfire Detected (Emission) Signal Rate of Change Above Threshold	An emission deterioration misfire occurs (2 trip detection logic).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on	DTC stored	SAE Code: -
P0300-85	Random / Multiple Cylinder Misfire Detected (Over Temperature) Signal Above Allowable Range	A misfire occurs that may damage the three-way catalytic converter (2 trip detection logic).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: -
P0301-00	Cylinder 1 Misfire Detected	Misfiring of a specific cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: P0301
P0302-00	Cylinder 2 Misfire Detected	Misfiring of a specific cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: P0302
P0303-00	Cylinder 3 Misfire Detected	Misfiring of a specific cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: P0303
P0304-00	Cylinder 4 Misfire Detected	Misfiring of a specific cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Port fuel injector assembly Direct fuel injector assembly Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored	SAE Code: P0304

When DTCs for misfiring cylinders are randomly stored, but DTC P0300-00 is not stored, it indicates that misfires have been detected in different cylinders at different times. DTC P0300-00 is only stored when several misfiring cylinders are detected at the same time.