if the boiler is flashing 04 its a fault code telling you that there is insufficient water pressure, you need to locate the filler loop and increase the water pressure to 1.5 bar approx. filler loop is usually a silver flexible pipe located under or near the boiler, open the small valve or valves either side untill the pressure guage reads approx 1.5 bar, you also may need to reset the boiler.
dean, June 2007
