Your boiler is currently showing its water temperature and is likely waiting for you to check the system pressure before it resumes normal operation.

Indicative flow temperature to CH. O.K. Scroll to pressure display "P". Press RESET button to scroll display

What causes this fault?

This code appears when the boiler's internal sensor detects that the water temperature has reached a certain level and is now waiting for user confirmation of the system pressure. It often occurs after a period of heavy use or if the system has recently been refilled, requiring you to manually toggle the display to ensure there is enough water in the unit. The boiler effectively pauses until it is sure the pressure is within the safe operating range.