Your boiler’s solar heating panel sensor has a wiring fault, meaning the system cannot correctly read the temperature of the water heated by the sun.

Control mode - Solar: Collector temperature sensor shorted out

What causes this fault?

This fault occurs when the electrical circuit for your solar roof panels is broken or compromised, preventing the boiler from receiving a temperature reading. The most common reason is that the sensor probe has failed internally or the wiring has been damaged by pests or extreme weather exposure. In some cases, the connection at the boiler's control board may have simply become loose or corroded.