BoilerFaultCodesYour boiler is firing up, but it doesn't detect the water getting hotter quickly enough, so it has shut down to prevent itself from overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Dry fire - Flow/return temperature sensor change too small
What causes this fault?
This fault occurs when the boiler's internal computer registers that the burners are on, but the temperature sensors fail to detect a significant rise in heat within the water. The most common reason is a lack of water circulating through the system, often caused by a pump failure, a blockage, or even just too much air trapped in the pipework. Because the boiler cannot move the heat away from the burner quickly enough, it shuts down to prevent 'dry firing' and damaging the internal components.
This fault is more frequent in autumn when the heating is turned on for the first time after summer, as circulation pumps are prone to seizing or sticking after long periods of inactivity.
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 bar on the digital displayEnsure all radiator valves (TRVs) are turned to the highest settingTop up the water pressure using the filling loop if it is too low
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F.83 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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