Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to shut down for safety.

Flow–NTC: – NTC broken – NTC cable broken – Defective connection at NTC – Defective connection at electronics | Flow–NTC cable defective/broken NTC faulty

What causes this fault?

This fault occurs when the boiler's main control board loses the electrical signal from the sensor that monitors hot water leaving the unit. The most common reason is that the sensor itself has internal electrical failure or the wiring connecting it to the circuit board has become loose or damaged over time.