The fault finding section from the install manual (attached) note the reference to different rates of lamp flashing to give different faults
if the boiler is noisy before it shuts down or if the hot water is cold will be a blocked plate heat exchanger
did you find a solution mamte as i have just posted this also. WORCESTER BOILER 28 SI II Hi, I wonder if anybody could help me please, My Worcester 28 SI II will cut out after filling half a bath, then the red light flashes, after resetting it just trips again straight away and again and again. Same happens with central heating, it will run for 20 mins then cut out and wont reset. However here is the weird bit, if I then leave it for 40 mins or so to cool down it will again fill half a bath or will heat house for 20 mins. Its 9 years old and had a new pcb 6 years ago, this does sound to me like a dry joint again on the pcb or even a diode or capacitor that expands when the pcb gets hot. But im not the expert you are. I don?t want to replace the pcb and find out its just the same. Any ideas please?? Thanks all in advance.