BoilerFaultCodesYour boiler's internal computer has encountered a critical communication failure or hardware fault, meaning it cannot process commands to heat your home.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
What causes this fault?
This fault occurs when the boiler's central brain and its memory chip stop talking to each other, often due to an electrical failure or a loose internal connection. The most common reason is that the Heat Control Module—a small plug-in component that stores the boiler's specific settings—has failed or become corrupted. When this link is broken, the boiler shuts down immediately as a safety precaution because it no longer knows how to operate the burner correctly.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F0258 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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