How to Understand ECU diagnostics

Engine management may be more of a subject for modern Fords or modified classics with an aftermarket fuel-injection system, but it’s also relevant to a number of stock classics. Ford’s Electronic Engine Control (EEC) computer dates back to the ’70s and by the time version five (known as EEC-V) appeared in the mid ’90s, it was reading data from a wide range of familiar sensors (crank position, mass air flow) to help control fuelling and ignition timing. Plus, it was OBDIIcompliant (on-board diagnostics version two), which was a standard of communication that had to be fitted to cars in the US by law from 1996 onwards to ensure fault codes could be identified and problems could be fixed using a range of universal code readers. Prior to this, communicating with a car’s ECU was limited to using dedicated equipment that was only available at Ford dealerships and which often incurred a hefty plug-in fee. Unfortunately, the UK and Europe took a little longer to adopt OBDII, so most post-2001 petrol engine vehicles and post-2003/4 diesels are compliant. However, Ford Europe seemed to have adopted this universal means of communicating with an ECU by around 1997 for petrol engines. So what does this mean for anyone with a late Escort, Fiesta, Ka or Mondeo for example? Well,