This code is not actually an error, but a display setting that shows which external device or auxiliary pump is currently connected to your boiler's secondary circuit.

Technical description

Function of relay 1 (multi-functional module): 1=Circulation pump, 2=External pump, 3=Cylinder charging pump, 4=Extractor hood, 5=External solenoid valve, 6=External fault message, 7=Solar pump (omitted), 8=eBUS remote control, 9=Legionella protection pump, 10=Solar valve