Crown Victoria, Grand Marquis, Town Car, 2006-2007

Knock Sensor



The operation of the Knock Sensor (KS) is to monitor pre-ignition or "engine knocks" and send the signal to the PCM. The PCM responds by adjusting ignition timing until the "knocks" stop. The sensor works by generating a signal produced by the frequency of the knock as recorded by the piezoelectric ceramic disc inside the KS. The disc absorbs the shock waves from the knocks and exerts a pressure on the metal diaphragm inside the KS. This compresses the crystals inside the disc and the disc generates a voltage signal proportional to the frequency of the knocks ranging from zero to 1 volt.

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Fig. Two types of Knock Sensor

Removal & Installation

Vehicle fuel systems are pressurized even when the engine is not running. To avoid fire or personal injury, disable the fuel delivery system and relieve fuel system pressure before removing any fuel system component. Refer to the fuel system information at the beginning of pinpoint HC. Failure to follow these instructions may result in personal injury.

For access to the Knock Sensors, refer to Engine Mechanical Components-Intake Manifold-Removal and Installation.

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  1. Remove the 2 Knock Sensor bolts, and remove the Knock Sensors.
  3. To install, tighten the Knock Sensor bolts to 18 ft. lbs. (25 Nm).


Knock Sensor Pin Testing

For reference values, refer to PCM testing-PCM reference voltage chart

This pinpoint test is intended to diagnose the following:

Knock sensors KS1, KS2 (12A699)
Harness circuits: KS1+, KS1-, KS2+, and KS2-

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