Sounds like the EGR (Exhaust Gas Re-circulation) valve. Looks like it's easier to get off the 1.6l version of this engine if the picture in the Haynes manual for the Fiesta (which uses the same engines) is correct. On the 1.4l version, the EGR valve is bolted to a port on the back of the cylinder head - well out of sight. On the 1.6l, the EGR valve appears to be mounted on the left of the air cleaner box, where the EGR elbow is on the 1.4l version. But the Haynes manual is very hazy on this. For a second opinion, just drive to your local supermarket and ring your breakdown service, AA or RAC or whatever. Tell 'em that your engine management light is on and you don't want to drive it untill you know it's OK to continue. They will come and read the fault code. Or you could buy your own Fault Code Reader such as the Sealey VS8700 for about forty quid from your local car parts shop. If the code is P0404, that is the commonly occuring 'EGR Performance' and after a few long runs, and it hasn't spotted bad 'EGR performance' for a while, then the dashboard light will go out. That code often comes in if you do a lot of stop-start driving one day. If it's a fault which will not clear of it's own accord and the EGR valve will come off easily, then just clean it out with a can of EGR cleaner, brake cleaner or carburetter cleaner (all much the same stuff). If a new EGR vave is fitted, then according to the Haynes manual, It has to go to the dealer to have the valve 'initialised'. Don't they just make life so easy for you these days?