Your boiler has lost the ability to measure the temperature of your tap water, meaning you will likely have no hot water until the sensor is fixed.

Domestic hot water (DHW) temperature sensor failure – possible error with electronic card or the NTC sensor.

What causes this fault?

This fault occurs when the boiler's internal computer loses communication with the sensor responsible for monitoring your tap water temperature. The most common reason is that the sensor itself has developed an electrical fault or has worn out, though loose wiring or a failure on the main control board can also stop the signal from being received.