BoilerFaultCodesTechnical description
Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing
What causes this fault?
This fault occurs when the boiler's main brain and its specific identity chip fail to communicate or suffer an internal electronic crash. It is usually caused by a loose connection following a recent repair, or the internal circuitry of the control board simply failing due to age. Without this digital handshake, the boiler stays off to prevent it from operating with incorrect safety parameters.
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.
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