Your boiler's controls have temporarily lost their connection to each other, so it may not respond properly to your thermostat or settings until this is fixed.

DIY fix possible

Turn off the boiler at its on/off switch and at the fused spur or isolator, then wait about 5 minutes.Turn the power back on and wait a few minutes to see whether the fault code clears and the boiler resumes normal operation.If the code returns, check that any cables plugged into the boiler's control panel or the room thermostat are fully pushed in, then restart. Do not open the boiler casing; if the fault persists, call a Gas Safe registered engineer.