Your boiler has developed a communication or hardware circuit error that has caused it to stop providing both heating and hot water.

Boiler is not working for central heating or hot water and the display shows ‘HHHHH:::::AAAAA ’ (flashing).

What causes this fault?

This fault occurs when the boiler's internal communication system suffers a total breakdown, essentially meaning the different electronic parts can no longer 'talk' to each other. The most common reason is a physical failure within the main circuit board or a malfunction in the control knobs that prevents the boiler from receiving instructions. Because the brain of the boiler cannot verify the system is safe or functional, it shuts down entirely as a precaution.