BoilerFaultCodesTechnical description
Overheat thermostat operated
What causes this fault?
This fault occurs when the internal water temperature exceeds a safe limit, causing the boiler to shut down for safety. The most common reasons are a pump failure that stops water from moving or a blockage in the system pipes that prevents heat from being carried away from the boiler quickly enough.
This issue is more frequent during the first cold snap of autumn when a pump that has been idle all summer suddenly seizes or struggles to circulate water through the radiators.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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