on my 4 cyl 1998 C class engine the ignition coil has to be removed from the spark plugs by unscrewing four screw on two of the four plug leads,

be sure to remember the wiring route so you can reconnect properly,

it is nice to have one of those plastic ties handy to replace the one you need to cut to work on the wires.

be careful to install the new plugs with stripping any threads, and use a torque wrench to final the tighness.