BoilerFaultCodesYour boiler has switched itself off because it has reached an unsafe temperature to protect the internal components from damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat fault
What causes this fault?
This fault occurs when the water inside the boiler gets too hot, causing a safety sensor to trip and shut the system down. The most common reasons are a pump failure that stops water from circulating or a buildup of sludge and debris that restricts flow through the heat exchanger.
This fault is more common when the heating is first turned on in autumn, as pump components can seize up after being idle throughout the summer.
DIY fix possible
Check that all radiator valves are fully open to allow water to circulateEnsure the boiler pressure gauge is between 1 and 1.5 barPress the reset button once to see if the fault clears after the system has cooled down
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 F5 — 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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