BoilerFaultCodesA safety switch or an external control, such as a thermostat or a condensate pump, has tripped and told the boiler to stop running.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The external switching contact has opened
What causes this fault?
This fault occurs when a safety device connected to the boiler’s control board has broken the electrical circuit to stop the unit from running. The most common reason is a blocked condensate pump that has reached its limit and sent a signal to prevent an overflow, or an external thermostat that has malfunctioned. Essentially, a secondary safety device has stepped in to shut the system down for protection.
This fault is frequently seen during cold snaps when external condensate pipes freeze, causing the pump to backup and trigger the safety switch.
DIY fix possible
Check if your thermostat or programmer is calling for heat and has working batteries.If you have a condensate pump, check if it is full of water or blocked.Ensure all external switches or emergency stop buttons near the boiler are in the 'On' position.
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