BoilerFaultCodesTechnical description
All Heating Zones locked
What causes this fault?
This fault occurs when the boiler’s main computer loses touch with your heating controls or receives conflicting information about how many heating zones it should be managing. It is essentially a 'handshake' failure where the boiler disables the heating to prevent damage because it no longer knows which part of the house is calling for heat. The most common reasons are a loose connection in the wiring, a failed external thermostat, or a software glitch on the main circuit board.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register →