This is indicating that the temperature of your last batch was too low/high.
The unit can adjust for temperatures between 65-100 degrees farenheit.
While the unit will continue to function this is a warning that the efficiency of the unit is being effected.
If you are getting this fail message and the temperature is in range then temp probe has probably failed.
To test the probe do a continuity test. If it is open it needs to be replaced. #616-28