Knock Sensors - Basics about Knock Sensors

The knock sensor is a piezoelectric accelerometer that acts as a microphone on the engine. It converts vibrations into alternating current (AC) signal. When the crystal inside the sensor is vibrated, it produces an AC voltage.
The greater the vibration or shock, the higher the voltage and frequency. In this video we discuss how a knock sensor can fail, testing and diagnostics.
The greater the vibration or shock, the higher the voltage and frequency. This video was created by Babcox Media and Tech Minute and is sponsored by NGK Spark Plugs.

[@jf8461]

Can a noisy tappet or lifter trigger the knock sensor?

[@Barrys_Workshop]

Great information thanks

[@arthurserino2254]

A knock sensor is NOT an accelerometer, that is a completely different device. The knock sensor is a contact microphone that listens for pinging. An accelerometer measures changes in velocity.

[@ivankulcsar2151]

If it's not an accelerometer, why are specs in mV/g?

[@arthurserino2254]

@@ivankulcsar2151 Piezoelectric microphones also are rated in millivolts per gram.

[@jacksonprice4080]

THANK YOU!!!!❤😍😍😍

[@atomicdmt8763]

excellent. To be clear: the (5V) is sent out as a circuit CHECK only... and the ECU will then receive (~2.5V) signal from the sensor during all other operation? My sensor is a single wire type. THANKS

[@rvrv5028]

I have a 2013 mazada demio and am not getting any ignition and no start and all the fuse is working.can the knock sensor causes that to happen or the manifold intake?