BoilerFaultCodesWhat the manual says
Manufacturer manualFailed overheat – the overheat thermostat needs checking
What causes this fault?
This fault occurs when the internal temperature of the boiler exceeds safe limits, triggering a safety sensor to cut off the burner. The most common reasons are a pump failure that stops water from circulating, or a blockage within the heat exchanger that prevents heat from being transferred away from the unit.
This issue is more frequent in autumn when heating systems are first turned on after summer, as pumps can seize 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 04: no call-out fees, no surprise bills.
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