What is the function of the knock sensor in an engine?

The function of the knock sensor in an engine is to detect engine knock, which occurs when fuel ignites prematurely in the engine cylinder. This pre-ignition can cause damage to the engine if it is not controlled. The knock sensor is an important component because it monitors the vibrations and sounds produced by knock events and sends this information to the engine control unit (ECU). Once the ECU receives a signal indicating that knocking is occurring, it can adjust the ignition timing to prevent further knock events. By retarding the timing, the engine runs more smoothly, maintaining performance and protecting engine components from damage.

This functionality highlights the significance of the knock sensor in optimizing engine efficiency and longevity, which is why this option is the correct choice. Other options, while related to engine performance, do not serve the same function as the knock sensor.