BoilerFaultCodesYour boiler has detected that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent 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 overheat
What causes this fault?
This fault occurs when the internal temperature of the exhaust system exceeds safe limits, triggering a safety shut-off to protect the boiler. The most common reason is a buildup of limescale or debris inside the 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 blockage in the chimney-pipe or a faulty sensor giving an incorrect reading.
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 Slow flash (normally on, flashes off) / Flashing (reset required) — no call-out fees, no surprises.
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Worcester Bosch Greenstar 24i Junior is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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