Your boiler has detected a problem with its internal temperature sensors, meaning it cannot accurately measure how hot the water is and has shut down as a safety precaution.

Fault on Temperature Sensor

What causes this fault?

This fault occurs when the boiler's control board loses communication with the temperature sensor or receives an unrealistic reading. The most common reason is that the internal thermistor has physically degraded over time or developed a short circuit, preventing the unit from monitoring heat levels safely. In some cases, it can also be caused by loose or damaged wiring connecting the sensor to the main circuit board.