Your boiler has stopped working because its internal computer has detected a problem with the electronic circuit that manages the flame.

Internal control box error (flame circuit fault)

What causes this fault?

This fault occurs when the boiler's main control board fails to correctly process the signals required to manage and monitor the burner's flame. The most common reason is a physical failure of the internal electronics on the circuit board, though it can also be triggered by worn-out ignition parts or damaged wiring that disrupts the signal flow.