Your boiler is having trouble measuring the temperature of your hot water, which usually means it cannot heat water safely or effectively.

DHW Thermistor Fault

What causes this fault?

This fault occurs when the sensor responsible for monitoring your hot water temperature has failed or is sending incorrect readings to the main control board. The most common reason is that the internal components of the sensor have degraded over time, though it can also be caused by loose or damaged electrical wiring. Because the boiler cannot accurately tell how hot the water is, it shuts down as a safety precaution to prevent overheating.