BoilerFaultCodesTechnical description
Flue thermostat sensor tripped (lockout)
What causes this fault?
This fault occurs when the internal temperature within the flue reaches a dangerous level, triggering a safety sensor to shut the system down. The most common reasons are a build-up of debris or limescale in the heat exchanger which prevents heat from transferring to the water, or a physical blockage within the flue pipe itself.
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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