Models: All Mercedes-Benz models with coil-over-plug ignition systems.
To reduce the force required to plug or unplug the spark plug connector, apply grease before installing the spark plug connector. Otherwise, the spark plug connector may be damaged when it is removed at another time. Apply approximately one gram of the Mercedes-Benz Spark Plug Connector Grease (A 002 989 80 51) uniformly into the spark plug connector as shown in Fig 1.
Courtesy of ALLDATA.