BoilerFaultCodesTechnical description
Burner in fault state - Flue gas temperature limiter has responded
What causes this fault?
This fault occurs when the internal safety sensors detect that the exhaust gases leaving the unit are exceeding safe temperature limits, triggering an immediate shutdown to protect the internal components. The most common reasons are a build-up of limescale or debris inside the heat exchanger that prevents heat from being transferred to the water, or a fault with the temperature sensor itself. It can also be caused by the burner not firing correctly, leading to excessive heat buildup within the casing.
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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