Your boiler's internal sensor that monitors the temperature of water leaving the unit has stopped working correctly, and the system has shut down to prevent overheating.

Flow sensor error – sensor damaged, short circuited, sensor damaged or wiring broken

What causes this fault?

This fault occurs when the boiler's control board loses communication with the temperature sensor attached to the main heating pipe. The most common reason is that the internal sensor has physically degraded and failed, or the electrical wires connecting it to the main computer have become loose or damaged.