Stolen this from tgtt.com you are looking for the diagnostics socket, on a normal ep82 it sits on the rear right of the engine bay and has a plastic cap over it. Black box near nearside strut tower on ep91s i believe. to put the ecu into diag mode with the car off, first using a paper clip or similar you have to bridge out the TE1 and T1 connections. then turn the ignition on,don't start the engine. if there is a fault the ecu light flashes a number of times that will correspond to a fault code listed above eg 3 flashes, pause, 1 flash would indicate a code 31. If its a steady repeating flash its fine. Either pop on here of google 4efte ecu codes and you'll get a list of them