Your boiler has detected a problem with the internal temperature sensor that monitors the water leaving the unit, causing it to shut down as a safety precaution.

Flow Thermistor Fault

What causes this fault?

This fault occurs when the sensor responsible for measuring the heat of the water leaving your boiler fails to send a correct signal to the main control board. The most common reason is that the sensor has physically degraded or developed an electrical short, but it can also be caused by loose wiring or a glitch in the boiler's internal computer.