After 2 years its first fault is ignition lockout. The boiler runs the full 10 min in Service mode which suggest gas pressure and gas valve working ok, flue clear, ignition and electrodes working, no condensate issues, both CH and HW heat up during this time. Seals all in good order. Once cover back on and switched on again, after the 5 attempts it goes to reset. What am I missing please? Any suggestions appreciated. Thanks.