What is a Renault scenic knock sensor?

A knock sensor is a sensor inside an engine that detects detonation of fuel prior to the spark plug igniting the full during the cycles of the engines.

Detonation at the wrong time can cause significant harm to an engine since it will cause the piston where the detonation occurred to be pushed down at the incorrect time. This can result in a catastrophic breakdown of the whole engine. A knock sensor monitors irregular detonation and will automatically retard or advance the timing of the engine to ensure that serious damage is not caused to the motor.