Is the coefficient for the control instrument (instrument with oxygen probe signal input) set correctly? This coefficient has many different names: process coefficient, probe coefficient, coefficient, loop coefficient, calibration coefficient, etc. Adjusting this coefficient can reduce or eliminate the deviation between the displayed value and the actual process data acting on the workpiece. Are the probe's temperature value and O2 mV signal set to match the corresponding display signal on the controller? If not, it may be a calculation issue with the instrument. 5. Can the oxygen millivolt signal from the probe recover to 10% within 5 seconds after being short-circuited (if the instrument does not have a related display, a millivolt meter can be used for measurement)?