Your boiler is briefly keeping the internal pump running after the heating has switched off to cool down the internal components.

Heating system pump over run

What causes this fault?

This occurs because the boiler needs to dissipate residual heat from the internal heat exchanger once the heating or hot water demand has met its target. The system purposefully keeps the pump spinning for a few minutes to circulate water and prevent the internal components from overheating. It is a normal safety function of the boiler's operating cycle rather than a mechanical failure.