What is a Knock Sensor?

One of the questions recently asked was “What is a knock sensor?” Welcome to Mercie J Auto Care, where compassion and craftsmanship come together. I’m Rick Smith, master certified technician. Now a knock sensor or detonation sensor is used on many vehicles. Inside your engine is a lot of moving parts. One of those parts is the Pistons going up and down and if we happen to ignite the fuel a little too soon, that piston rocks back-and-forth and it makes a knocking sound or detonation or what we might also call as pinging. A knock sensor is a piezo electric device. These are also used for events where you have like disco or a concert and you have the beat of the music playing with the lights. These sensors sense of vibration such as a piston rattling in the engine or knock and that’s when they generate electricity. What we actually do to test them is we put them in a vice like this, hook up a scope to it and then we will create a knocking sound to see what kind of voltage it produces. That tells the computer that hey we have a pinging, detonation, knock whatever you want to call it and then it adjust things like timing appeal to compensate for that so we don’t do any engine damage. I hope this is an informational for you until next time safe travels and blessings to you.