Your boiler has experienced an internal computer failure and has shut down for safety, meaning it will no longer provide heating or hot water.

Automatic Lockout. Internal PCB failure discovered during self-check.

What causes this fault?

This fault occurs when the boiler's internal control center suffers a critical hardware failure or a short circuit on its circuitry. The most common reasons are electrical surges, general wear and tear of the components over time, or moisture ingress from a slow internal leak that has reached the sensitive electronic board.