Taken from PUK
FITV (Fast Idle Thermo Valve)
The valve itself is located just under the throttle body. Easiest way to get to it is to remove your intake pipework all the way up to the throttle body to expose the valve. This picture shows the valve at the bottom (you don't need to take your throttle body off Very Happy )
You can just about get at the three bolts with a spanner, then unclip the coolant hose and whip the valve off.
Take the metal plate off the front of the valve housing to expose the valve.
Then just unscrew the plastic valve retainer with a flat bladed screwdriver to release the valve.
Unclip the spring from the valve and it just comes apart. Give everything a blast with carb cleaner and re-assemble in the reverse of above. Tighten the plastic spool all the way down, then back it off a few turns.