Knock sensors, location - GF15.12-P-4101-01E

Engine 119 

1 knock sensor each on left and right of crankcase

Fig 1: Identifying Knock Sensors - Engine 119 (Right Side Of Engine)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Fig 2: Identifying Knock Sensors - Engine 119 (Left Side Of Engine)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.