Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold or slightly warm.

Hot water NTC sensor defective.

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring the temperature of your hot water fails to send a reliable signal to the main control board. The most common reason is natural wear and tear or corrosion on the sensor's probe, which prevents it from reading how hot the water is, causing the boiler to shut down the burner for safety. In some cases, it can also be triggered by a loose or damaged connection in the wiring that links the sensor to the rest of the unit.