BoilerFaultCodesWhat the manual says
Manufacturer manualOverheat thermostat fault detected by diagnostic feature.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety sensor to cut the power. The most common reasons are a failed pump that isn't moving water away fast enough or a blockage in the heat exchanger that traps heat. Sometimes, it can also be caused by a build-up of air or sludge in the system restricting flow.
This fault is more common when the heating is first turned on after summer, as pump components can seize up during long periods of inactivity.
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.
Avoid the next call-out bill
A cover plan would handle faults like Overheat: no call-out fees, no surprise bills.
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