BoilerFaultCodesTechnical description
Overheat thermostat tripped
What causes this fault?
This fault occurs when the internal temperature of the boiler rises above a safe limit, causing a safety sensor to cut the power. The most common reason is a blockage or a failing pump that prevents water from flowing through the system quickly enough to carry heat away from the burner. In some cases, it can also be triggered by a build-up of air or debris within the heat exchanger.
This issue often surfaces during the first cold spell of autumn when the heating is turned on after being dormant all summer, which can cause internal pump components to seize.
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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