Your boiler has detected an electrical fault with the internal temperature sensor that monitors the outward flow of water, causing the system to shut down for safety.

Short circuit - flow-NTC (< 130 °C) | NTC- plug shorted to casing NTC defective

What causes this fault?

This fault occurs when the electrical signal from the sensor that monitors the temperature of the water leaving your boiler is interrupted. The most common cause is a failure of the internal thermistor component itself, but it can also be triggered by damaged wiring touching the metal boiler casing or a failure on the main control board.