BoilerFaultCodesYour boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, preventing it from heating up properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Primary (flow) thermistor fault
What causes this fault?
This fault occurs when the boiler's internal computer receives an incorrect or missing signal from the sensor that measures how hot the water is. The most common reason is that the sensor has physically failed or 'drifted' out of its correct range, but it can also be caused by loose or corroded electrical connections 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.
Find a Gas Safe engineer
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