CO2 Sesnor Calibration Offset

Is there a way to enter a negative calibration offset on a CO2 sensor? I get an error for “unacceptable character”

Make sure to update t3000 and also the device firmware. then give it a try from the t3000 inputs grid. you should be able to enter both positive and negative offsets.

Update: Just logged into a C02 sensor and indeed you can calibrate negative offsets here: