BoilerFaultCodesWhat the manual says
Manufacturer manualThe burner thermostat has been activated.
What causes this fault?
This fault occurs when the water inside the heat exchanger becomes too hot, triggering a safety switch to prevent the unit from melting or exploding. The most common reasons are a failed pump that isn't moving water away quickly enough, or a build-up of sludge and debris that is blocking the flow within the system.
This issue often surfaces when the heating is first turned on after summer, as the internal pump can seize up after months 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 08: no call-out fees, no surprise bills.
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