What role does a spark plug play in an engine?

A spark plug plays a vital role in the ignition process of an engine. Specifically, it ignites the air-fuel mixture inside the engine's cylinders. This ignition occurs when the spark plug generates a high-voltage spark that creates combustion, which in turn produces the energy needed to power the engine.

This process is crucial for engine operation because, without the spark plug igniting the air-fuel mixture, the engine would not be able to generate the necessary power to function. Understanding this function helps illustrate the importance of proper spark plug maintenance and replacement, as faulty or worn-out spark plugs can lead to performance issues, increased emissions, and reduced fuel efficiency.

The other options describe different components and systems within the engine but do not correctly identify the function of the spark plug. For instance, controlling the fuel injection system pertains to other engine management components, while monitoring engine temperature relates to temperature sensors. Additionally, filtering contaminants from the oil involves the oil filter, not the spark plug. Thus, the spark plug's specific purpose in igniting the air-fuel mixture is what distinguishes its essential function in the engine.