Abstract: In a spark plug, whose shell is provided with an eccentrically positioned, full-length, longitudinal bore designed to hold an insulating element, parts of the shell having varying wall thicknesses and a pressure measuring device being located in a part of greater wall thickness. In order to simplify connection with the ignition cable or coil, respectively, and to avoid breakage of the insulator, the spark plug insulator is configured as a multi-piece element and comprise at least an upper piece carrying the high voltage connector, a lower piece adjacent to the combustion chamber, and an insulating intermediate element of flexible material, which is placed between the upper and the lower piece of the insulator.