Your boiler is staying in a cooling-down mode because it thinks the internal temperature is still too high after the heating or hot water has turned off.

pump / fan overrun

What causes this fault?

This occurs when the boiler keeps its internal pump or fan running after a heating cycle to safely dissipate leftover heat. It is usually a normal safety function, but if it persists, it may indicate that the water is struggling to move through the system due to a blockage or a pump that is beginning to fail. In some cases, a faulty internal sensor might also be tricking the boiler into thinking it is hotter than it actually is.