Your boiler's internal computer has lost communication with its identification chip or the chip installed is the wrong model for this unit.

Incompatible code plug – check if a correct code plug is installed and exchange or reconnect code plug

What causes this fault?

This fault occurs when the boiler's main control board cannot communicate with a small, specific electronic chip called a code plug, which tells the boiler exactly which model it is. The most common reason is that the plug has become loose due to vibrations or has suffered an internal electronic failure. In some cases, this happens during a repair if an incorrect replacement part has been installed.