When the temperature on the sign is off by a few degrees, you may be able to adjust the Temperature Offset. Click on file then Communications. Inside of the Communication window click on Sign Config and change the Temperature Offset. Then click on Update Display Settings.
If the temperature is off more than a few degrees, then you may need to have the temperature probe replaced or the wire (and/or wire nuts) replaced. Click Here are some tips for testing the temp probe.
The best place for the temperature probe to be installed is on the north side of the building and in the shade.