Knock Sensor (KS)

The knock sensor is installed on the cylinder block, and senses knocking that occurs in the engine. The sensor is a piezo-electric type which converts vibration resulting from knocking into electric signals. In addition to a piezo-electric element, the sensor has a weight and case as its components. If knocking occurs in the engine, the weight in the case moves causing the piezo-electric element to generate a voltage. The knock sensor harness is connected to the bulkhead harness.

Fig 1: Identifying Knock Sensor (Baja, Forester, Impreza 2.5L, Legacy, Outback 2.5L & Outback Sport)

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Fig 2: Identifying Knock Sensor (Impreza WRX 2.0L)

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Fig 3: Identifying Knock Sensor (Outback 3.0L)

Courtesy of SUBARU OF AMERICA, INC.