BoilerFaultCodesYour boiler has stopped working because it cannot safely get rid of waste gases or excess water through its external pipes.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: 1 Check if condensate pipe blocked/frozen 2 Check if flue blocked 3 If fault persists, contact installer
What causes this fault?
This fault occurs when the boiler detects that it cannot safely expel exhaust gases through the flue or drain away waste water through the condensate pipe. The most common reasons are an external blockage in the pipes, such as debris or ice, which triggers a safety sensor to shut the system down to prevent damage or dangerous fumes.
This fault is significantly more common during freezing winter temperatures, as the external condensate pipe can freeze and prevent water from leaving the boiler.
DIY fix possible
Check the external plastic condensate pipe for signs of ice or blockages and thaw with warm water if frozen.Inspect the flue outlet on your outside wall to ensure it isn't obstructed by debris, leaves, or bird nests.Restart the boiler using the reset button once any external obstructions are cleared.
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A boiler cover plan would cover faults like Blocked Flue/Condensate — no call-out fees, no surprises.
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Could it be time for a new boiler?
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