First, the calibration begins without warmup. And the data may change a little after the module is warm.
Second, the pressure of the standard gas is too high.
Third, the zero setting pipe is not extended to place with no CO2, so appropriate Zero canít be reached.
Forth, when density value is being entered, the module is clearing Zero at the same time. Therefore, the density of air without CO2 is mistaken for that of 5%. In this case, no wave form shows on the monitor when using the pipeline, as in fact, the wave is too high.
Fifth, the module chip of memory data digital gain is damaged, but a rare case.
Sixth, the atmospheric pressure sensor is damaged, so wrong atmospheric data is collected, which may cause deviation when calculating the CO2 density. So, it is suggested that you check whether the software reading is around 760mmHg before the calibration.