BoilerFaultCodesYour boiler has switched itself off because it became too hot, acting as a safety precaution to prevent damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat thermostat has operated. Requires pressing O/H reset button and checking system.
What causes this fault?
This fault occurs when the internal water temperature exceeds a safe limit, causing the boiler to shut down to prevent internal melting or component failure. The most common reasons are a lack of water flow caused by a failing pump or an airlock, though it can also be triggered if the sensors themselves become faulty.
This fault is more frequent during the first cold spell of autumn, as central heating pumps often seize up after being left idle throughout the summer months.
DIY fix possible
Check that your radiator valves are open and not blockedEnsure there is enough water pressure in the system (if applicable)Locate the overheat reset button under the control panel cover and press it firmly
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 OVERHEAT FAULT — no call-out fees, no surprises.
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Ideal Concord CXA 40-120 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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