BoilerFaultCodesTechnical description
Failed flue temperature – check operating system
What causes this fault?
This fault occurs when the internal sensor detects that the gases leaving your boiler are reaching dangerously high temperatures, triggering a safety shutdown. The most common cause is a buildup of debris or limescale inside the main heat exchanger, which prevents heat from being transferred to your water properly and instead sends it out through the flue. It can also be caused by a faulty sensor sending an incorrect temperature reading to the boiler's computer.
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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