Why does a once passed probe calibration status report failed after a certain time frame?z

It is recommended that the probe calibrations be done any time the probe has been changed at least once a week. The Probe calibration will go failed after around a month's time as the calibration log results get purged after 30 days. It is up to the customer how frequent the probe gets calibrated, but following the recommended guidelines above will ensure you always have a good and current calibration.