BoilerFaultCodesYour boiler is shutting down because it is heating up much faster than it should, usually due to water not flowing through the system properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety or flow temperature rising too fast
What causes this fault?
This fault occurs when the water inside the boiler heats up too quickly because it isn't being moved away into your radiators or hot taps fast enough. The most common reasons are a pump that has stopped working, a blockage of sludge or limescale in the pipework, or air trapped within the system.
This issue often appears when the heating is first turned back on in autumn, as pumps can seize after being inactive throughout the summer.
DIY fix possible
Check that your radiator valves are fully openEnsure the central heating system pressure is between 1.0 and 1.5 barBleed all radiators to remove trapped air that might be blocking flow
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like NO CODE 212 — no call-out fees, no surprises.
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