Your boiler is currently running a brief automatic safety check to confirm its internal water levels before it allows your heating or hot water to start.

DIY fix possible

Wait for the check to complete (usually takes less than 1 minute)If the code persists, check the boiler pressure gauge is between 1 and 1.5 barIf pressure is low, top up the system using the filling loopPress the reset button if the code remains on screen for an extended period