The knock sensor detects vibrations that come from a knock or an irregularity in combustion and send a signal to the engine control computer, which then adjusts timing to correct the knock.
What will a bad knock sensor do?
A bad knock sensor may also not let the engine accelerate properly while driving on the highway, and cause the vehicle to lose fuel mileage. Once the computer realizes the knock sensor is not working properly, your vehicle will most likely lose power.
Can a knock sensor cause a knock?
The knock sensor might have to blame. When the ignition timing is insufficient, it can cause unnecessary knock or ignition resulting in lower gas mileage.
What does a knock sensor tell you?
The purpose of the knock sensor is to sense unusual pulsations caused by the engine detonation. It is basically the computer's ear to the engine to determine if it is working properly. If the knock sensor detects an abnormality, the computer will let you know with the Check Engine Light.