Abstract: Electronic theft prevention apparatus for vehicles including an engine containing spark plugs for providing ignition, a high voltage source and a distributor having a central contact for providing high voltage distribution to the spark plugs, the apparatus including; decoder apparatus disposed within a protective housing enclosing the central contact, encoder apparatus accessible to a vehicle operator for providing coded instructions to the decoder, data coupling apparatus for interconnecting the decoder apparatus and the encoder apparatus to permit data transfer therebetween, whereby application of constant battery voltage to the data coupling apparatus is not effective to operate the decoder, and switching apparatus located within the protective enclosure, operated by the decoder and governing the supply of a high voltage input to the central contact, thus selectably preventing high voltage distribution to the sparkplugs.