New Holland CX720 Operator's Manual page 199

SECTION 2 – CONTROLS, INSTRUMENTS AND OPERATION
Message: "Calibration successful"
3. The calibration is done.
Remark: If an error occurs while calibrating the zero
returns volume, the calibration procedure will be
aborted and an error code will appear on the screen.
Error
23 Threshing not engaged
52 Threshold
54 Engine not at high idle
68 No signal
2–126
Possible cause Remedy
Engage threshing
Clean pivotable return plate
Set engine to high idle
221