Your boiler is simply letting you know that the pre-heat feature is active to provide hot water to your taps more quickly.

DIY fix possible

No action is required as this is an advisory status message, not a breakdown code.If you wish to turn this off to save energy, locate the 'Comfort' or 'Warm Start' setting in your menu.Turn the hot water temperature dial slightly down and then back to your desired heat to toggle the status.