Depending on the reason for the misfire, a misfire can occasionally be fixed. However, the misfire will frequently continue until the underlying problem is resolved. The engine control module stores the code P0303, which refers to a misfire in cylinder number 3, when it notices that the engine is not operating smoothly in this particular cylinder. This causes the check engine light to illuminate on the dashboard. It must be fixed as quickly as possible because it could harm the catalytic converter and other emissions systems.