BoilerFaultCodesYour boiler has detected a problem with one of its internal temperature sensors, causing the system to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow Thermistor Fault
What causes this fault?
This fault occurs when the boiler's internal computer loses communication with the temperature sensor attached to the main heating pipe. The most common reason is that the sensor has physically degraded or developed a short circuit, meaning the boiler can no longer safely monitor how hot the water is. Occasionally, this can also be caused by loose wiring or a connection issue between the sensor and the main control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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