The cooling fan on my Neff fan assisted oven runs continuously even when the oven has fully cooled down after cooking. The only way to stop it is to switch the electrics off completely.
The model is a B1432

Roy Withey, July 2007

Could be that your overheat thermostat could be open circuit, causing your oven to think that the temp in the oven is still rising causing the cooling fan to remain on a simple continuity test on the stat will determine this, the stat is usually locatated on the top of the oven just behind the display panel maybe under a cover.

john, July 2007