BoilerFaultCodesTechnical description
Flue NTC sensor over temperature
What causes this fault?
This fault occurs when the internal temperature sensor detects that the exhaust gases are getting far too hot, triggering an immediate shutdown to protect the boiler's internal plastic components. The most common reason is a buildup of limescale or debris inside the main heat exchanger, which prevents heat from transferring into your water and sends it out through the flue instead. It can also be caused by a lack of water circulation or a faulty sensor giving an incorrect reading.
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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