Some Ford Fusion owners report experiencing issues related to a check engine light caused by a cylinder 3 misfire, which can lead to symptoms like rough idling, reduced fuel economy, and engine stalling. Additionally, concerns about a blown head gasket are common, as this can result in coolant leaking into the engine, causing overheating and white smoke from the exhaust. Some owners also report issues with a cracked cylinder, leading to loss of compression and further misfires. Repair costs for addressing a cylinder 3 misfire typically range from $100 to $500, but in severe cases involving coolant leaks and corroded plugs, a total engine replacement may be necessary. Common symptoms associated with this misfire include excess vibration, reduced power, and potential fuel mileage issues. The P0303 diagnostic trouble code specifically indicates a misfire in cylinder 3, which can result in power loss and potential damage to the catalytic converter. It is crucial for owners to address these issues promptly to prevent further engine damage and ensure optimal vehicle performance and safety.