Knock sensor component description - GF07.04-P-6030V

ENGINE 272.920 in MODEL 203 up to Model Year 8

ENGINE 272.922 in MODEL 211

ENGINE 272.940 in MODEL 203 up to Model Year 8

ENGINE 272.941 in MODEL 203 up to Model Year 8

ENGINE 272.942 in MODEL 171 up to Model Year 8

ENGINE 272.943 in MODEL 211, 219

ENGINE 272.944 in MODEL 211

ENGINE 272.945 in MODEL 251 up to Model Year 8

ENGINE 272.946 in MODEL 221 up to Model Year 8

ENGINE 272.960 in MODEL 203 up to Model Year 8

ENGINE 272.963 in MODEL 171 up to Model Year 8

ENGINE 272.964 in MODEL 211, 219

ENGINE 272.965 in MODEL 221 up to Model Year 8

ENGINE 272.966 in MODEL 230 up to Model Year 8

ENGINE 272.967 in MODEL 164, 251 up to Model Year 8

ENGINE 272.970 in MODEL 203 up to Model Year 8

ENGINE 272.972 in MODEL 211

ENGINE 272.975 in MODEL 221 up to Model Year 8

ENGINE 272.985 in MODEL 211, 219

ENGINE 273.922 in MODEL 221 up to Model Year 8

ENGINE 273.923 in MODEL 164 up to Model Year 8

ENGINE 273.924 in MODEL 221 up to Model Year 8

ENGINE 273.960 in MODEL 211, 219

ENGINE 273.961 in MODEL 216, 221 up to Model Year 8

ENGINE 273.962 in MODEL 211

ENGINE 273.963 in MODEL 164, 251 up to Model Year 8

ENGINE 273.965 in MODEL 230 up to Model Year 8

ENGINE 273.967 in MODEL 209

ENGINE 273.968 in MODEL 221 up to Model Year 8

ENGINE 272.940 in MODEL 209

ENGINE 272.960 in MODEL 209

Location

The knock sensors are located at the top of the crankcase under the intake manifold.

Fig 1: Locating Knock Sensors

Courtesy of MERCEDES-BENZ USA

Task

The knock sensors detect combustion knocks at excessively high vibrations at the crankcase. Anti-knock control thereby corrects the ignition timing for each individual cylinder when the engine is warm.

Body

The knock sensors function according to the piezo ceramic principle. The screened cables are connected directly to the knock sensors.

Fig 2: Identifying Knock Sensor Signal Patterns Of Controlled And Uncontrolled Combustion

Courtesy of MERCEDES-BENZ USA

Function

Any vibrations which occur are converted with the aid of the piezo ceramic into electrical signals.

Piezo-electric effect: If a mechanical force acts on a crystal, electrical voltages are produced.

The noise signal is modulated to a DC voltage from 0.13 to 4.7 V for transmission to the ME control unit.

Knock sensor signals may also indicate engine damage, e.g. increased engine noise resulting from a widened piston groove.