When knocking occurs, the weight in the cylinder case moves, causing the piezo electric element in the KS to translate the vibration into an electric voltage. A signal is then transmitted from the KS to the ECU. In response, the control unit retards spark timing to prevent engine knocking.
On the Loyale with Multi-Point Fuel Injection (MPFI), the KS is located on top right-side of the cylinder block and senses knock signals from each cylinder.
On the Legacy and Impreza, the KS is installed on top left-side of the cylinder block and senses knock signals from each cylinder.
The SVX is equipped with 2 knock sensors; both are located on top of the cylinder block — one on the right side and one on the left side.