Your boiler has shut down multiple times because it reached a dangerously high temperature and is recording how often this safety limit has been triggered.

Number of safety temperature cut offs

What causes this fault?

This fault occurs when the boiler's internal water temperature exceeds safe limits, forcing the system to shut down to prevent damage. The most common reason is a lack of water circulation, often caused by a failing pump or a blockage in the heat exchanger that prevents heat from leaving the unit. It can also be triggered by faulty sensors that are incorrectly reading the system temperature.