Hey Kids... I have just been reading this article by Jim Mais about the diagnostic plug found in the engine bay. http://www.nls.net/mp/volks/htm/plug.htm I have known that it was used by VW techs to diagnose electrical faults but I was surprised to note that it was also used to analyse engine compression and ignition timing too. I'm curious as to whether the plugs are still useful to us or were special analysing gizmos needed to read the data from the plug. Phill.