BoilerFaultCodesYour boiler has switched itself off because it has become too hot inside, usually due to a blockage or a pump failure preventing water from circulating.
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 safety tripped
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety switch to prevent damage. The most common reason is that the water isn't moving through the system quickly enough, often due to a failed pump, a blockage of sludge, or air trapped inside the heat exchanger.
This fault is more common when you first turn the 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.Ensure there is enough water pressure displayed on the boiler gauge (typically 1.0 to 1.5 bar).Press and hold the reset button for five seconds once the boiler has cooled down.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E02 — 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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