(480) 830-9445                      

Photo of the Mercie J Crew

What is a Knock Sensor?

One of the questions recently asked was “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.


Thank you for visiting Mercie J Auto Care in Mesa serving: Mesa, Gilbert, & Apache Junction, AZ where we love our customers and their kids!  Expect Hot Wheels Racing, Great Customer Service & Excellent Mechanics who know how to fix anything that comes through these bay doors!   Our goal is to have everyone of EVERY age to leave happy!

Schedule your appointment today (480) 830-9445 or REQUEST APPOINTMENT HERE.

Mercie J Auto Care llc

1730 N Banning St.
Mesa, AZ 85205

location small (480) 830-9445
Email the Shop


Mon - Thur:   8:00 AM - 5:30 PM
Fri - Sun: CLOSED

Make An Appointment



© Program, Specialty Pages, Content for Auto News Blog, Page Layout, and CMR EasyNews Programming by CMR, Inc a JSP Website or Top Auto Website