BoilerFaultCodesYour boiler has sensed that the exhaust gases are getting too hot and has shut down 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: Flue gas temperature is too high.
What causes this fault?
This fault occurs when the internal sensors detect that the waste gases leaving your boiler have reached an unsafely high temperature. The most common reasons are a significant build-up of limescale or debris inside the heat exchanger, or a lack of water flow preventing the heat from being transferred away from the unit effectively.
This issue is more common during winter when the boiler is running at maximum capacity for long periods to heat both the radiators and hot water simultaneously.
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 F003 — 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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