BoilerFaultCodesYour boiler has likely overheated, causing a safety switch to trip and shut the system down to protect itself.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety Thermostat Operated
What causes this fault?
This fault occurs when the water temperature inside your boiler gets too high, triggering a safety switch to prevent damage. The most common reason is a lack of water flow, often caused by a failing pump or a blockage within the main heat exchanger. It can also happen if there is trapped air in the system or if the internal safety sensor itself has developed a fault.
DIY fix possible
Check that your radiator valves are open and not turned to the off position.Ensure there are no blockages in the system such as trapped air by venting (bleeding) your radiators.Wait for the boiler to cool down and press the 'Reset' button.
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 E110 — no call-out fees, no surprises.
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Potterton Promax Combi HE Plus is discontinued — time for a new one?
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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