BoilerFaultCodesTechnical description
Heat control module (HCM) potentially defective – reset the appliance
What causes this fault?
This fault occurs when the boiler's main control board loses its connection with the internal identity chip that stores the appliance's specific settings. It is often caused by a temporary electronic glitch or a physical failure of the heat control module itself, which prevents the boiler from knowing how to safely fire up. Because the brain cannot verify the boiler's hardware, it shuts down the system as a safety precaution.
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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