Knock Sensor Failure Symptoms
 

What would be the noticeable impact on engine performance if one or both knock sensors malfunction? My understanding is that if the sensor detects knocking it produces an input to the ECU which then retards the ignition timing on the cylinder bank experiencing the knocking. I am "guessing" that such a situation would be short lived and that the timing would be returned to normal quickly once the knock dissipates.

Does the sensor produce a voltage output when knocking occurs? If it malfunctions, can it trigger ignition retardation that persists long enough to be felt in engine vibration or some other parameter?

I did not replace either of the two knock sensors on my 3.6, and am now second guessing whether I should have replaced them during my rebuild.

Check your knock counts with either a Hammer, PST-2, or PIWIS to see if those values are abnormal or not.

Here's a nice article on knock sensors

Engine Knock Sensors, Part 2 - Diagnostic News

Notable info on how it works: Two major knock sensor designs are used today: broadband single-wire and flat response two-wire knock sensors. Both sensor designs use piezoelectric crystals to produce and send voltage signals to the ECM.