BoilerFaultCodesTechnical 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 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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