Your boiler has stopped working because its internal temperature sensor has lost contact with the pipework or is failing to send a signal.

Central heating NTC not connected to pipe

What causes this fault?

This fault occurs when the boiler's main control board can no longer detect an accurate temperature reading from the flow pipe. The most common reason is that the clip-on sensor has physically vibrated loose or a internal wire has become disconnected, preventing the boiler from safely monitoring heat levels.