Your boiler has switched itself off because it has reached an unsafe temperature and needs to cool down before it can restart.

Over heat cut off activated | Cause: Maximum temperature exceeded

What causes this fault?

This fault occurs when the water inside the boiler gets too hot, triggering a safety switch to prevent damage. The most common reason is that the water isn't moving through the system quickly enough, often due to a pump failure or a blockage in the pipework. It can also happen if the sensors that monitor temperature become faulty and send the wrong information to the boiler control board.