Your boiler's internal memory card has developed a communication fault, meaning the control system cannot verify the specific settings for your model.

Boiler chip card (BCC) fault

What causes this fault?

This fault occurs when the boiler's main control board loses its connection with the small memory chip that stores your appliance's specific tuning profile. The most common reason is that the chip card has vibrated loose, failed electronically, or the main circuit board itself can no longer read the data required to operate safely.