Your boiler has lost communication with its internal computer chip, meaning the main control board no longer recognizes the specific model it is supposed to be operating.

BCC Fault

What causes this fault?

This fault occurs when the boiler's main control board loses the vital data connection to its identity chip, effectively 'forgetting' which model it is. The most common reason is a loose or failing Boiler Chip Card (BCC) that has vibrated out of place or suffered a small electrical surge that corrupted its memory.