DTC P0305 - Cylinder 5 Misfire Detected
DTC P0306 - Cylinder 6 Misfire Detected
DESCRIPTION
Text in Illustration
When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can
cause increases 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 these increases 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 VVT sensor and the crankshaft position sensor. The VVT 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 level and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.
When DTCs for misfiring cylinders are randomly set, 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.
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