Your boiler is briefly running the pump after heating your water to cool down the internal components and prevent them from overheating.

What causes this fault?

This occurs when the boiler has finished heating your hot water and needs to move the remaining heat away from the internal heat exchanger. It is a standard safety feature where the pump continues to run for a short period to protect the internal components from heat stress. This is part of the boiler's normal cooling cycle and does not indicate a breakdown.