Component description for the knock sensor - GF07.04-P-6030CY

ENGINE 272.911 in MODEL 204.0 up to Model Year 8

ENGINE 272.921 in MODEL 204.0 /2 up to Model Year 8

ENGINE 272.947 in MODEL 204.0 /2 up to Model Year 8

ENGINE 272.948 in MODEL 204.0 up to Model Year 8

ENGINE 272.961 in MODEL 204.0 /2 up to Model Year 8

ENGINE 272.971 in MODEL 204.0 up to Model Year 8

Location

Knock sensors are located under the variable intake manifold on the crankcase.

Fig 1: Identifying Right And Left Knock Sensor

Courtesy of MERCEDES-BENZ USA

Task

Knock sensors detect vibrations on the crankcase (combustion knocking) for knock control.

Knocking can also be an indication of engine damage (e.g. increased engine noise resulting from widened piston grooves).

Knock sensor signal

Function

Vibrations on the crankcase are converted by the internally-mounted piezo crystals of the Knock sensors into electrical DC voltage signals (from 0.13 to 4.7 V).

The DC voltage signals are transmitted via a 2-pin shielded line directly to the ME-SFI [ME] control unit (N3/10).

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

Fig 2: Identifying Knock Sensor Signal Waveform

Courtesy of MERCEDES-BENZ USA