BoilerFaultCodesTechnical description
Flue NTC Operated
What causes this fault?
This fault occurs when the sensor inside the exhaust flue detects that the heat leaving the boiler is dangerously high. The most common reason is a buildup of debris or limescale inside the main heat exchanger, which prevents heat from transferring into your water and forces it out through the flue instead. It can also be caused by damaged internal insulation or a faulty sensor providing an incorrect reading.
This fault is more common during the winter months when the boiler is running at maximum capacity for long periods to meet heating demands.
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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