BoilerFaultCodesYour boiler has switched itself off because it has reached a dangerously high temperature, likely due to a lack of water or poor circulation.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner in fault position. Flue gas temperature limiter has responded. Check the heating system water level and the pump. Vent the system.
What causes this fault?
This fault occurs when the boiler's internal components detect that the heat being produced isn't being carried away quickly enough, causing the system to overheat. The most common reasons are a failed internal pump that isn't moving the water, or a significant blockage within the heat exchanger that is restricting flow. It can also be triggered by a large pocket of trapped air or a dangerously low water level in the system.
This fault often appears during the first cold spell of autumn when a pump that has been idle all summer fails to restart or 'seizes' due to inactivity.
DIY fix possible
Check the pressure gauge and top up the water if it is below 1.5 barBleed all radiators to remove trapped air from the systemEnsure all radiator valves and isolation valves are fully openReset the boiler after checking water levels
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