BoilerFaultCodesTechnical description
Optional thermostat intervention
What causes this fault?
This fault occurs when an external safety device triggers to prevent the system from getting dangerously hot. It usually happens because water is not moving through the boiler quickly enough, often due to a pump failure or a blockage in the heating pipes. When the heat cannot be carried away from the boiler, the temperature spikes and the safety thermostat cuts the power to prevent damage.
This issue is more frequent during the first cold spell of autumn when a pump that has been idle all summer fails to start up again.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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