Guts of the dreaded knock sensor

[Lokim]

I was curious how they worked, so here are some pics of the guts of the 22060-30P00 knock sensor:

Assembled -


Disassembled, top 4 layers -


Disassembled, bottom 3 layers (the part on the left is the 4th layer from previous photo) -


It seems to me that the mode of failure is the solder that holds the resistor between the two terminals melts away
due to heat cycling, causing the sensor to read increased resistance, lose continuity, or short together.

Just in case anyone was curious (Paul...)

[Skibane]

As I understand it, the "resistor" is a piece of piezo-electric material that briefly generates a voltage when exposed to certain mechanical sounds - sort of like a microphone that is tuned to "listen" for a very narrow range of sounds which indicate spark knock. The ECM measures the strength of these brief voltage pulses to determine if spark knock is occurring.

[Lokim]

Actually, the resistor was soldered between the 2 connector blades. When I ohmed it after disassemblijng it it read approx. 550K ohms. I know the piezo-electric material generates voltage when jarred (as in engine knock) but I think the resistor was there to create a load so the circuit would not be read as a short.

[Infinitiguy19]

I dare you to put the Knock Sensor back together again and put it under the plenum of the Q!

Thanks for this though.

[Lokim]