Just done a oil change on car and found this pipe,does anyone know what it is or where it goes if anywhere?.The cars a ford focus saloon 2000 1.8tddi engine.

I think it's a charcoal canister hose.
Look for a round black unit with a wiring block on top at the back of the engine near the scuttle panel. (left side as you look into the engine bay).
Failing that it may be the vacuum hose from the EGR.

I found a picture on google and it goes to the airfilter.
thanks