Your boiler has detected an internal sensor failure and has stopped providing hot water or heating to protect the system.

Temperature sensors faulty (DHW and CH sensors)

What causes this fault?

This fault occurs when the boiler's control board can no longer accurately read the temperature because the internal sensors have failed or become disconnected. Over time, these small probes can degrade due to constant heat cycles or moisture, leading them to provide incorrect signals that force the system to shut down for safety.