Your boiler's internal computer has lost its configuration settings and no longer knows which model it is supposed to be operating.

Jumper tag fault

What causes this fault?

This fault occurs when the boiler's main control board loses the vital identity settings that tell it how to manage gas and water flow for your specific model. It is typically caused by a loose or failing physical jumper plug on the circuit board, or a sudden electrical surge that has scrambled the board's internal memory. Without this configuration, the boiler enters a safety mode because it no longer knows its own operating limits.