BoilerFaultCodesYour boiler has sensed that the exhaust gases are becoming too hot and has shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flue sensor overheating
What causes this fault?
This fault occurs when the internal temperature of the exhaust fumes exceeds safe limits, triggering a safety cutout to prevent damage to the plastic flue components. The most common reasons include a buildup of limescale or debris inside the main heat exchanger, which prevents heat from being transferred to the water effectively, or a faulty sensor sending incorrect readings to the control board.
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 E22 — no call-out fees, no surprises.
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