The knock sensor is designed to sense when fuel is burning unevenly
and causing "knocking" or irregular vibrations in the engine.
The knock sensor consists of an electric coil that is wound around two
ceramic rods with a magnet in the center. Engine vibration makes the
ceramic rods vibrate. This disturbs the coils magnetic field and
alters the current passing through the coil. This disturbance returns
to the computer as a signal pattern that the computer analyzes. The
computer then determines whether the vibrations are characteristic of
engine knocking.
