BoilerFaultCodesYour boiler has detected a fault with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: HEATING THERMISTOR ON FLOW PIPE: CIRCUITS OPEN OR SHORT CIRCUIT. CHECK RESISTANCE OF THE THERMISTOR. (12500 ohms AT 20°C. 1750 ohms AT 70°C).
What causes this fault?
This fault occurs when the internal sensor responsible for measuring the water temperature as it leaves the boiler fails or loses its connection to the main control board. The most common reason is that the sensor's internal electrical components have degraded over time or a wire has become loose, preventing the boiler from knowing if it is overheating. As a safety precaution, the system stops firing because it can no longer accurately regulate the heat level.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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