11/10/2025
⚠️The term misfire refers to the failure of combustion in one or more engine cylinders. When this occurs, the ECU records a diagnostic trouble code that identifies which cylinder is misfiring. Codes P0301, P0302, P0303, and P0304 follow a logical sequence: the last digit indicates the number of the affected cylinder. For example, P0301 corresponds to cylinder 1, P0302 to cylinder 2, and so on.
⚠️If the misfire is intermittent and a jerk or loss of power is noticed when accelerating, the first thing to check is the ignition coil. If the misfire ""moves"" when swapping the coil with another cylinder, this is a clear sign that the coil is the culprit. In many modern engines, the coil is integrated with the wire and connects directly to the spark plug.
⚠️When the coil is in good condition, but the cylinder still doesn't fire, the fuel injector should be checked. If the injector doesn't open properly or is clogged, the cylinder won't receive fuel, and even if there is a spark, there will be no combustion. In this case, the engine may smell of unburned gasoline or a dry spark plug.
⚠️Finally, if both the coil and injector are operational, it's necessary to remove and check the spark plug. A sulfated, carbon-coated, or worn plug can prevent sparking or cause poor ignition. Replacing or cleaning it, depending on its condition, can correct the misfire and restore the affected cylinder to working order.
