BoilerFaultCodesYour boiler has become too hot and has automatically shut down to prevent damage or danger.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat cutoff operated
What causes this fault?
This fault occurs when the water temperature inside the boiler exceeds a safe limit, triggering a safety sensor to cut the power. The most common reasons are a pump failure that prevents water from moving, or a blockage caused by internal sludge that traps heat within the main heat exchanger.
This fault often appears during the first cold spell of autumn when the heating is turned back on after months of inactivity, which can cause internal pumps to seize up.
DIY fix possible
Check that your radiator valves are open to allow water to flow.Verify that your system pressure is between 1.0 and 1.5 bar on the gauge.Press the 'Reset' button (often a flame symbol with a cross through it) once the boiler has cooled down.
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 F.20 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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