Bad electrical contacts, burner control unit UBA 3 is defective or KIM is defective.

Solution

1 - Check the contact between:

The UBA3 burner control unit and the UBA3 mounting base by screwing the UBA3 burner control unit firmly onto the UBA 3 mounting base;

The control panel BC10 and the base plate of the control panel BC10 by pressing the control panel BC10 firmly onto the base plate;

All other plug connections and solve any contact problem.

Does the same error message now appear?