Timing and temperature are crucial in a vehicle's ignition system in order for combustion to occur correctly and for the engine to perform at its best. In an engine, when fuel is not ignited properly/at the right time it produces an explosion that can ruin the finely-tuned cycle of the engine, and can lead to damaged engine components. These little explosions are referred to as engine knock or detonation, and produce a knocking or pinging sound in the engine. The engine knock sensor functions to detect harmful engine vibrations caused by engine knock and this information is used to determine ignition timing and prevent further detonation.

Positioned on the intake manifold, engine block or cylinder head, the engine knock sensor works by sending a signal to the car's ECU (Electronic Control Unit) which will use this information to adjust the ignition timing to protect the engine from what is known as pre-ignition; the fuel combusting and burning before it is ignited by the spark plug. 

If the fuel burns in the engine before it should, usually due to the engine's compression being too low, this can lead to a build-up of carbon deposit and debris. When these deposits accumulate in the cylinder head, the air and fuel mixture does not have enough space, leading to compression being too high in the cylinders, which results in engine knock. The engine-knock-sensor functions to detect when this is happening and with the help of the ECU avoid this pre-ignition.

If there is a problem with the engine knock sensor the warning light should illuminate on the dashboard of the car. Signs of a malfunctioning engine knock sensor can include a loss of acceleration and the vehicle not achieving as many miles to the gallon as usual.  It's advisable to seek advice from a mechanic to establish the exact cause of the fault. When you need to replace this part, the engine knock sensor is the ideal choice, designed to be compatible with the make and model of your vehicle.