BoilerFaultCodesTechnical description
Flue gas thermostat fault or fan fault
What causes this fault?
This fault occurs when the boiler's main control board suffers an internal electronic failure or a loss of communication with its connected sensors. It is usually caused by aging electrical components on the circuit board wearing out or, in some cases, a loose connection in the internal wiring harness. Because the 'brain' of the boiler can no longer process safety data, it shuts down the system entirely to prevent accidents.
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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