BoilerFaultCodesYour boiler’s internal computer chip is unrecognized or has been installed incorrectly, causing the system to stop working for safety reasons.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: error – incorrect HCM fitted
What causes this fault?
This fault occurs when the boiler's main control board cannot communicate with the small data chip that identifies the specific model and power output. The most common reason is that this chip has worked loose from its socket, or it has been replaced with a version that is incompatible with the rest of the components. Because the system doesn't know exactly which model it is, it shuts down as a safety precaution to prevent incorrect operation.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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