Replace the spark plugs in a Mercedes-Benz C200 by removing the two-piece engine cover, removing the coil packs via the 12 Torx bolts and replacing the six spark plugs. Reassemble the parts by reversing the order in which they were removed.
The tools needed for this task are a 3/8-inch ratchet with 3- and 6-inch extensions, a 3/8-inch driver, a 5/8-inch spark plug socket, a T30 Torx bit (preferably socket style), a torque wrench and a strong adhesive tape like duct tape. To remove the plastic engine cover, slide the front section away from the rear, and lift it off the rubber mounts below. Remove the two air intake hoses connected to the rear engine cover by pulling them off, then remove the rear engine cover by pulling upward on each corner.
Remove the 12 Torx bolts that attach the coil packs to the engine, and pull the coil packs from the cylinders carefully as not to damage the wiring. Attaching the 6-inch extension and spark plug socket to the ratchet, wrap duct tape around the socket so that it holds the socket and extension together, which prevents the socket from falling off. Replace the spark plugs, torquing each one to factory specifications if a torque wrench is available.