my vaillant plus 837e has come up with error code f33 what does this mean and what should be done to put it in the right working order

perci, December 2009

Call a Gas Safe Register Installer in your area to rectify the fault. F33 is Fan/Air Pressure Switch. Check the flue is clear and if the fan spins but the boiler doesn't fire... it is probably the Air Pressure Switch.
Not a hard job to change- parts readily available.... no more than 10/15mins if it's the case. Parts are not expensive.
Had to do one this evening as my last job!!!!!
Hope this helps.

Neil-675, January 2010