BoilerFaultCodesYour boiler's internal computer has developed a fault and can no longer control the heating or hot water safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: PCB Fault: Replace PCB
What causes this fault?
This fault occurs when the boiler's main control board experiences a critical electronics failure or a memory corruption error. The most common reason is natural wear and tear of the electrical components over time, or damage caused by an external power surge or moisture ingress.
While this fault can happen year-round, it is slightly more common during winter storms when power outages and electrical surges are more frequent.
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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F09 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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