[zabatron]

Dont need to access the diagnostic port to read diagnostic codes on wp/wq fiesta ....Just press down and hold the trip meter reset button,and turn on ignition key to position where all red warning lights are on on the dash/instruments.Once you see the word "TEST"appear in the in information panel of instrument cluster,release the trip meter reset button and your car will be in diagnostic mode.Then continue to press and release trip meter reset button to scroll through the pages of information/tests until you see "DTC" on the information panel screen.If any diagnostic codes are present,the code(or codes) will appear below the word "DTC" on the screen.If no codes are present it will say "none'.Then record any codes that are present,and just google search them to find out what the codes relate to.To exit diagnostic mode,simply turn ignition key to off position.Above procedure can be performed with engine off or on(you can even drive car in diagnostic mode).
I know this works as I have done the above heaps of times on my WQ XR4.