Technical description
Starting point adjustable from 1 to 10K below the set value
What causes this fault?
This fault occurs when the boiler's control system identifies a mismatch in its internal operational settings, specifically regarding the temperature drop allowed before it fires up again. It is typically caused by a minor electronic glitch within the main control board or a slight calibration error in the temperature sensors. While the boiler continues to function, it is highlighting that its internal logic for managing heat cycles is slightly out of sync.
DIY fix possible
Press the 'Reset' button on the control panelTurn the boiler off and back on at the fused spur switchMonitor the display to see if the code clears after a restart