Your boiler has lost its ability to measure the temperature of the water leaving the unit, usually due to a faulty sensor or a wiring issue.

Central heating flow NTC fault

What causes this fault?

This fault occurs when the boiler's internal computer can no longer detect a reliable signal from the sensor that monitors the temperature of the water being sent to your radiators. The most common reason is that the sensor itself has failed internally due to age, or the electrical connection between the sensor and the main control board has become loose or damaged.