BoilerFaultCodesYour boiler has shut down because it detected that the exhaust gases are getting too hot, which is a safety feature to prevent internal damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety switch-off – flue gas temperature too high
What causes this fault?
This fault occurs when the internal safety sensors detect that the waste gases leaving your boiler have reached a dangerously high temperature. The most common reason is a buildup of debris or limescale inside the main heat exchanger, which prevents heat from being transferred to your water and instead sends it out through the flue. It can also be caused by a faulty sensor sending incorrect readings to the boiler's computer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F.25 — 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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