Hi Zander & lads When starting and not starting all the measuring blocks are th same except for "Engine start permitted-0" and "Engine ecu response-0"(these are both 1 when it starts). I hadn't noticed this before you suggested it,would this aim at the immobilizer control unit and is there any way of checking this ? The cable from the reader coil goes to a small box located beside the back of the light switch,i presume this is the immobilizer control unit?? This is my first issue with an immobilizer so a little lost at the minute,doesnt help with the customer only living 2 minutes away & constantly on my doorstep !