Vaillant Turbomax No Water/Warmstart/Heating S.33 Error?

Hi,

I have moved into a house with this dreadfull boiler. Hot water has been intermittent i.e takes ages to warm up, and hot showers soon turn into cold ones.

But things have gone worse and I cant get it to work at all. When it goes into ignition mode for either hot water or cold water I get a S.33 status. Which means to check Air/Flue.

After reading the trouble shooting guide I have found it could be either the Air Pressure Switch, or The Electronic Circuit Board [ECB].

Have any of you had this and how have you fixed it?

Thanks

Chris