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: Appliance overheat
What causes this fault?
This fault occurs when the water inside the heat exchanger reaches an unsafe temperature, triggering a safety sensor to cut the power. The most common reasons are a failed pump that isn't moving water around the system or a blockage of sludge and debris restricting the flow. Sometimes, a faulty sensor can also trick the boiler into thinking it is overheating when it actually isn't.
This fault is more common in autumn when heating systems are switched back on after a long summer break, often causing internal pump components to seize.
DIY fix possible
Wait at least 20 minutes for the boiler to cool down naturally.Ensure all radiator valves (TRVs) are fully open to allow water to flow.Turn the mode selector switch to the 'OFF/RESET' position, wait a few seconds, then turn it back to the original setting.
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