Kia Optima: Knock Sensor (KS). Description and OperationWhen knocking occurs, the vibration from the cylinder block is applied as pressure to the piezoelectric element. When a knock occurs, the sensor produces voltage signal. The ECM retards the ignition timing when knocking occurs. If the knocking disappears after retarding the ignition timing, the ECM will advance the ignition timing. This sequential control can improve engine power, torque and fuel economy.

Installation
Knock Sensor (KS). SpecificationsTachometer
The tachometer indicates the approximate number of engine revolutions per minute
(rpm).
Use the tachometer to select the correct shift points and to prevent lugging
the engine and/or overrevvin ...
General Service Information
Protection Of The VehicleAlways
be sure to cover fenders, seats, and floor areas before starting work.
The support rod must be inserte ...
Seat belt warning (for driver’s seat)
The driver's seat belt warning light and chime will activate to the following
table when the ignition switch is in "ON" position.
*1 Warning pattern repeats 11 times with an inter ...