essential information required before diagnosis
boiler make?
boiler model?
whether problem affects CH or DHW or BOTH?
more than ONE fault indicator light?
sequence of flashes[slow, fast,etc]?
do you have an installation & servicing manual for boiler?
does it have a fault finding section in the back?
if you cant even give me the boiler make & model
then i'm afraid this is a dead end
manwithnoname, May 2011