Part of any internal combustion engine is a set of spark plugs which are responsible for creating small explosions to ignite the fuel mixture in the car, and beginning the combustion process that produces energy enough to power the vehicle to drive. Regular checkups always include inspecting the spark plugs for any malfunction. A spark plug is a component that delivers electric current from an ignition switch to the combustor of a spark-ignition engine, allowing an electric spark to ignite the compressed fuel/air combination while keeping combustion temperature within the engine under control. A spark plug features a metal thread shell with a ceramic insulator electrically isolating it from a center electrode. A substantially insulated wire connects the center electrode, which may contain a resistor, to the output node of an ignition coil or magneto. The metal shell of the spark plug is inserted into the cylinder head of the engine, making it electrically grounded. The central electrode juts into the combustion chamber via the porcelain insulator, generating spark gaps between the central electrode’s inner and outer ends. When not firing, spark plugs in Saab Direct Ignition are utilized to monitor ionization in the cylinders; this electrical currents measurement replaces the typical cam position sensor, knock sensor, and mistake measurement function.   Spark plugs can also be utilized in other situations where a flammable fuel/air combination has to be ignited, such as furnaces. They sometimes are referred to as flame igniters in this scenario.