BoilerFaultCodesYour boiler's internal computer has suffered a critical failure and can no longer control the heating system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Replace control board
What causes this fault?
This fault occurs when the boiler's main control board suffers a hardware failure or a memory error, meaning it can no longer process data or send instructions to parts like the pump or fan. The most common reasons for this are age-related component wear or an electrical surge that has damaged the delicate circuitry inside the control box.
This fault is often seen after summer storms or during the first cold snap of winter, as electrical spikes from lightning or the sudden strain of restarting the heating can push a failing circuit board to the point of collapse.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like Fast flash — no call-out fees, no surprises.
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Worcester Bosch Greenstar 12i System is discontinued — time for a new one?
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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