Your boiler's internal clock has lost track of the time or date, so timed heating and hot water schedules may not run correctly, but the boiler itself is usually still safe to use.

DIY fix possible

Check the date and time shown on the boiler's control panel and see whether they are wrong.Use the control dial and buttons to set the correct date, time and day of the week, following the menu in your user manual.Confirm your heating and hot water timer programmes are still correct, then switch the boiler off at the control panel for 30 seconds and back on to clear the message.