Your boiler’s control board has lost its identity settings, meaning the internal computer no longer knows which specific model it is supposed to be operating.

No valid DSN in display and/or main board. Spare part failure display and main board interchanged at same time and device specific number not adjusted

What causes this fault?

This fault occurs when the boiler's internal computer experiences a data mismatch or memory loss regarding its own model settings. The most common reason is that a replacement part was installed without being programmed correctly, or a power surge has corrupted the software communication between the main control board and the display unit.