BoilerFaultCodesYour boiler's internal computer has encountered a critical communication error and cannot safely operate your heating or hot water.
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 – the control box connections need checking
What causes this fault?
This fault occurs when the boiler's main brain loses the ability to talk to its internal memory chip, which contains the specific settings for your appliance. The most common reason is a physical failure of the electronic circuits or a loose connection between the internal control modules that prevents the boiler from identifying itself. Because the boiler no longer knows its own safety parameters, it shuts down completely as a protective measure.
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 F0239 — 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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