The spark plug is an important component of the ignition system of a gasoline engine. It can introduce high-voltage electricity into the combustion chamber and cause it to jump across the electrode gap to generate sparks, thereby igniting the combustible mixture in the cylinder.

1. Misfire: If the spark plug cannot flash normally, the combustible mixture in the cylinder will not be able to ignite, causing the engine to misfire.
2. Power decrease: If the spark plug flashover is unstable, the operation of the engine will be affected, resulting in a decrease in power.
3. Decreased fuel economy: If the spark plug does not work properly, it will cause the engine's fuel economy to decrease.
4. Engine shake: If the spark plug does not work properly, the engine will run unstable, causing the engine to shake.
5. Increased emissions: If the spark plug does not work properly, the engine's emissions will increase, causing pollution to the environment.