Your boiler's computer has lost its internal identification settings, preventing it from knowing how to operate correctly.

Invalid product code (DSN)

What causes this fault?

This fault occurs when the boiler's main control board and the display screen are not compatible or have not been properly introduced to each other. It usually happens after a repair where one of these parts was replaced but the unique software code for your specific boiler model wasn't entered. Without this identity code, the two components cannot communicate and the boiler will not fire up for safety reasons.