Your boiler has shut down because the water inside is getting much hotter than it should be, which is often caused by a blockage or a pump failure preventing the heat from moving away.

Flow temperature too high

What causes this fault?

This fault happens when the water leaving the boiler heats up too quickly or exceeds safe limits, causing the system to shut down for safety. It is usually caused by a pump failure or a blockage within the pipes that prevents hot water from circulating away from the boiler's heat exchanger. In many cases, it is the result of 'sludge' or debris building up over time and restricting the flow of water.