Your boiler has detected a problem with the sensor that monitors the temperature of the water leaving the unit to heat your radiators.

Central heating flow NTC fault

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring the heat of the water going to your radiators fails or sends an unreadable signal. The most common reason is that the sensor has physically degraded over time or a small leak has caused corrosion on the electrical connections. Without an accurate temperature reading, the boiler shuts down as a safety precaution to prevent overheating.