BoilerFaultCodesYour boiler has stopped working because it cannot safely get rid of exhaust fumes or waste water, often due to a blockage or a frozen pipe.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Ignition Lockout: Blocked Flue/Condensate
What causes this fault?
This fault occurs when the boiler's sensors detect a blockage that prevents exhaust fumes from leaving the flue or waste water from exiting the condensate pipe. The most common reason is a buildup of debris in the internal trap or an external pipe blockage, causing the system to shut down for your safety. In some cases, a faulty sensor or ignition component may also be incorrectly reporting a blockage.
This fault is significantly more common during freezing winter temperatures, as the external condensate pipe can freeze and cause water to back up into the boiler.
DIY fix possible
Check the white plastic condensate pipe outside for ice and thaw it with warm (not boiling) water.Check that the external flue terminal is not obstructed by debris or snow.Reset the boiler by turning the control knob to 'RE' or pressing the reset button.
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