Your boiler has temporarily paused operation because it has detected an unusual reading, and it will restart itself once conditions return to normal.

DIY fix possible

Check if your radiators are bled and the system pressure is between 1 and 1.5 barWait for 10-15 minutes to see if the boiler clears the code and restarts automaticallyEnsure any external vents or flues are not obstructed by debris