BoilerFaultCodesYour boiler has switched itself off for safety because it has become too hot and needs to cool down before it can be reset.
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 switch to shut the system down. The most common reasons are a failed external pump that isn't moving the water away fast enough, or a buildup of limescale and sludge that restricts flow through the heat exchanger.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after being idle all summer, which can cause internal pumps to seize.
DIY fix possible
Turn the boiler selector switch to the 'Reset' position and hold for 5 seconds, then turn it back to 'On'.Check that your radiator valves are open and that there is no air trapped in the system.Ensure the external system pump is running if visible and that there are no obvious leaks.
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