New Holland CX720 Operator's Manual page 188

SECTION 2 – CONTROLS, INSTRUMENTS AND OPERATION
Remark: If an error occurs while calibrating the
concave position, the calibration procedure will be
aborted and an error code will appear on the screen.
Error
20 Concave opening not correct
21 Concave position sensor error
22 Actuator error
Possible cause Remedy
Potentiometer giving invalid value, check
opening
Check sensor
Check with the drum concave clearance
button if the actuator is still moving
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