Your boiler has detected an issue with the sensor that measures the temperature of the water leaving the unit, preventing it from heating your home safely.

Flow Thermistor Fault

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring the heat of the water leaving the boiler fails to send a clear signal back to the control board. The most common reason is that the sensor has physically degraded or developed an electrical short, meaning the boiler can no longer safely tell if the water is getting too hot. In some cases, loose wiring or a connection issue between the sensor and the main computer can also trigger this shutdown.