BAXI Bermuda 552?

If the Pilot flame is a Sharp Blue colour, which envelops the end of the Thermocouple, which should glow dull red, then yes, the Honeywell V4600C Gas Control is probably faulty. BE WARNED THIS SHOULD ONLY BE REPALCED BY AN RGI.
www.gassaferegister.co.uk will help you to find a RGI near you

www.elanar.co.uk
July 2009

It may well be the gas valve, you can replace the power pack in it (the bit the thermocouple screws into) and it's cheaper than the full thing. It should be done by a qualified engineer.

Ian
July 2009