Your boiler has detected an electrical fault with an internal temperature sensor, preventing the system from monitoring heat levels safely.

Short circuit of the temperature sensor at the heating block – temperature sensor may need replacing

What causes this fault?

This fault occurs when the boiler's internal computer receives an incorrect electrical signal from the sensor that monitors the water temperature. This is usually caused by the sensor failing internally due to age or heat stress, or moisture getting into the electrical connections and causing a short circuit.