Your boiler has detected a temporary internal communication error or a sensor synchronization issue that is preventing it from running properly.

Temporary fault code (Refer to section 7.10)

What causes this fault?

This fault occurs when the boiler's internal control board loses track of the temperature readings because the signals from the sensors are inconsistent or mismatched. It is often caused by a failing hot water sensor sending incorrect data or a minor electronic glitch on the main circuit board that prevents the components from communicating correctly.