Your boiler has lost its connection to the external heating controls, meaning it cannot receive instructions on when to turn on or off.

Break communication to FX sensor controls electrical connections need checking.

What causes this fault?

This fault occurs when the boiler's internal computer loses its digital handshake with your room thermostat or programmer. The most common reason is a hardware failure in the wireless receiver plugged into the boiler front, or degraded electrical wiring that physically links the controls to the main circuit board.