Your boiler has sensed a problem with its internal temperature sensors or a lack of water movement, causing it to shut down for safety.

Control / no flow thermistor fault

What causes this fault?

This fault occurs when the boiler detects a sudden, unexpected rise in temperature because water isn't moving through the heat exchanger quickly enough. The most common reasons are a failed internal pump, a physical blockage like sludge in the pipework, or a faulty sensor that is sending incorrect temperature readings to the main computer.