BoilerFaultCodesYour boiler has detected an electrical connection issue or a safety sensor has tripped to prevent the exhaust gases from getting too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Electrical connection in cable loom (red / red-brown) disconnected. Flue gas thermostat (option) is activated or is defective.
What causes this fault?
This fault occurs when the boiler's safety system detects that the exhaust gases have reached a dangerous temperature, or if the electrical circuit that monitors this is broken. It is often caused by a buildup of limescale inside the heat exchanger or a loose connection in the internal wiring that prevents the control board from receiving a steady safety signal. In some cases, the sensor itself may have failed and is incorrectly reporting an overheat situation.
This fault can be more frequent during winter when the boiler is running at maximum capacity for long periods, leading to higher internal temperatures.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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