Your boiler's hot water sensor has malfunctioned, meaning the system can no longer accurately measure the temperature of the water coming out of your taps.

Hot Water NTC Fault

What causes this fault?

This fault occurs when the thermistor responsible for measuring your hot water temperature has failed or is sending an incorrect electrical signal to the control board. The most common reason is that the sensor has either degraded over time due to heat stress or has developed a small internal short circuit. This prevents the boiler from knowing how hot the water is, causing it to stop heating for safety reasons.