DTC P0300: Random / Multiple Cylinder Misfire Detected; DTC P0301: Cylinder 1 Misfire Detected; DTC P0302: Cylinder 2 Misfire Detected; DTC P0303: Cylinder 3 Misfire Detected; DTC P0304: Cylinder 4 Misfire Detected; DTC P0305: Cylinder 5 Misfire Detected; DTC P0306: Cylinder 6 Misfire Detected; DTC P0307: Cylinder 7 Misfire Detected; DTC P0308: Cylinder 8 Misfire Detected: Description

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbons concentration levels can cause an increase in exhaust emission levels. 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 exceeds the threshold levels and may cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

DTC No.	DTC Detection Condition	Trouble Area
P0300	Simultaneous misfiring of several cylinders occurs and one of the following conditions below is detected (2 trip detection logic): High temperature misfire occurs in three-way catalytic converter (MIL blinks) Emission deterioration misfire occurs (MIL illuminates)	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly for direct injection Fuel injector assembly for port injection Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve clearance Valve timing PCV valve and hose PCV hose connections Intake system ECM
P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308	Misfiring of specific cylinder occurs and one of the following conditions below is detected (2 trip detection logic): High temperature misfire occurs in three-way catalytic converter (MIL blinks) Emission deterioration misfire occurs (MIL illuminates)	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly for direct injection Fuel injector assembly for port injection Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve clearance Valve timing PCV valve and hose PCV hose connections Intake system ECM

If DTCs that indicate misfires are set for different cylinders, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.