I left you an answer earlier will leave my e-mail for if you have any other questions :)
It would be advised to also change the hot water sensor (captive} and central heating (thats the clip on 1 on the right of the combustion chamber) as these are a constant source of many failures and cost very little.I would replace these first and if no improvement replace that fan control board.
As always it is recomended that a compitent corgi registerd installer be used to carry out any repair to a gas appliance.( Thats a gas man covering his ass) LOL
wayneburgess@hotmail.co.uk
November 2008