Component description for a knock sensor - GF07.04-P-6030AMG

ENGINE 156.980 in MODEL 164, 251

ENGINE 156.982 in MODEL 209

ENGINE 156.983 in MODEL 211, 219

ENGINE 156.984 in MODEL 216, 221

Location

Knock sensor 1 is located on the right on the crankcase. It is protected against any strong effect of heat by a shield (removed in the picture).

Fig 1: Identifying Knock Sensor 1, Right

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Knock sensor 2 is located on the left on the crankcase.

It is protected against any strong effect of heat by a shield (removed in the picture).

Fig 2: Identifying Left Knock Sensor 2

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Task

The knock sensors detect vibrations for the purposes of knock control (combustion knocking) on the crankcase.

Knock sensor signals can also indicate engine damage (e.g. increased engine noise due to widened piston grooves).

Knock sensor signal

Function

Vibrations on the crankcase are converted by piezocrystals inside the knock sensors into electrical voltage signals (about 0.13 to 4.7 V). These signals are transmitted over a 2-pin screened line to the ME control unit (N3/10).

Fig 3: Identifying Knock Sensor Signal Pattern

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Piezo-electric effect: An electrical voltage is generated by the mechanical force on a piezo crystal.