Your boiler has detected that the water pressure inside the system has dropped too low to operate safely, causing it to shut down to prevent internal damage.

Dry fire

What causes this fault?

This fault occurs when the water level inside your central heating system drops too low for the boiler to function safely. The most common reason is a slow leak from a radiator valve or a pipe joint, but it can also happen if you have recently bled your radiators without topping the water back up.