Knock sensor

The knock sensor detects the combustion knock. If the knocking persists for a longer period, the pressure waves and thermal load can cause mechanical damage on the cylinder head gasket, on the piston and in the area of the valves.

Fig 1: Identifying Knock Sensor And Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The characteristic oscillations of knocking combustion are picked up by the knock sensor, converted into electrical signals and sent to the DME via the two connections.

In the DME, these signals are processed in such a way that enables assignment to the corresponding cylinder.