BoilerFaultCodesYour boiler has shut down because it has detected its internal temperature is getting too hot, usually caused by a blockage or a pump failure.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat sensor overheating
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, causing the safety sensors to shut the system down to prevent damage. The most common reasons are a failed pump that isn't moving water away from the heat exchanger quickly enough, or a buildup of debris and sludge that has physically blocked the internal pipework.
This issue often comes to light during the first cold spell of autumn when the heating is turned back on after being idle all summer, which can cause internal pump parts to seize.
DIY fix possible
Check that your radiator valves are fully open to allow water to flow.Check that your system pressure is between 1 and 1.5 bar on the gauge.Try resetting the boiler to see if the fault clears after the system has cooled down.
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A boiler cover plan would cover faults like E09 — no call-out fees, no surprises.
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