Your boiler is having trouble communicating with the internal water storage tank, which means your hot water supply may be affected or inconsistent.

Sensor/actuator fault on actoSTOR module

What causes this fault?

This fault occurs when the electrical signal from the hot water cylinder’s temperature probe is interrupted or corrupted. The most common reason is that the internal wiring of the sensor has failed or become damaged, causing a short circuit that prevents the boiler from knowing how hot your water is. In some cases, moisture ingress or loose connections at the sensor housing are the physical culprits.