Your boiler has detected that the water pressure inside the system is getting too high, which may cause a safety relief valve to drip or open.

DIY fix possible

Locate your radiators and find a radiator bleed valve with a square nut.Place a cloth and a container underneath the valve.Open the bleed valve slowly to release a small amount of water until the pressure gauge on the front of the boiler drops to between 1.0 and 1.5 bar.