Hi The car is an N Reg Cavalier Auto 70K miles The problem is that the ECU light is mostly on: occaisonally stays off often goes off at startup then comes back on after 2 seconds. I have seen references on this group to finding error codes with a paperclip ( seen AA man do this to this car but different fault) Where can I find the info on how to do this ? and can anyone suggest what the fault is. Thanks in advance Keith