BoilerFaultCodesYour boiler has become too hot and has shut itself down 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 Lockout
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power. The most common reasons are a pump failure preventing water from moving through the system or a blockage caused by a build-up of debris and sludge.
This fault is more common in autumn when homeowners first switch their heating back on after summer, as pump components can seize during long periods of inactivity.
DIY fix possible
Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough pressure in the system by checking the pressure gauge (aim for 1.5 bar).Press the 'Reset' button on the front of the boiler panel once the unit 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 4.2 — 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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