Boiler sequences through to main burner ignition but only for 5-7 secs.Boiler then recycles with similar results.
It has the new PCB Module fittrd(ie 1 LIGHT: Grreen/ Orange)
Burner flames pulsate and create some vibration( Lack of Air ???)
REmoval of Front Cover remedies problem.

Is the Fan on its way out ???
Its not blocked and it seems to be turning but thats when it does nor need to suck the air through the pipework and boiler casing.

Lawrence, February 2010

i had this problem on a potterton suprima and could get the boiler to fire by opening the door or making the air pressure switch make contact by blowing down the tube, it was a slow fan not creating enough pressure to make the air pressure switch connect, very deceptive because it sounded fine,i think its the fan you need to change

john, February 2010