I have a csi120 and every now and again the heating starts even though it isn't set to (even when only hot water switch is set). It then heats up and keeps heating until the radiators are too hot to touch (even though the boiler temp, not room temp is set to 57). It did it again last night and shut down with a code of 04, overheated.
My thoughts are it is the PCB. Maybe there are a dodgy batch..
Coasterphil
January 2011