Your boiler has sensed it is getting much too hot and has shut itself down to prevent damage or dangerous overheating.

Overtemperature protection intervention

What causes this fault?

This fault occurs when the internal temperature sensors detect that the heat exchanger has exceeded its safety limit, causing the boiler to shut down to prevent internal damage. The most common reason is a lack of water flow, often caused by a failing circulation pump or a blockage within the system that prevents heat from being carried away. In some cases, it can also be triggered by a buildup of limescale or debris inside the heat exchanger itself.