Knock Sensors

Q: What is a knock sensor?

A: Many new cars have “knock sensors”. Knock sensors on the engine identify when slight knocking begins to occur. Engine knocking can occur if too low of a fuel octane is used. The higher the octane rating the more the fuel resists knocking. When the sensor detects any knocking (it senses it by the vibration in the engine), it sends a signal to the car’s computer and adjusts the ignition timing. The adjustment of the timing eliminates the knock, but also compensates optimal engine performance (i.e., power and acceleration). Even though a knock isn’t audible to the ear, it may be occurring slightly.