What would be causing the sensor’s relative humidity readings to be much greater than an accurate reference’s readings?
There are three common sources for a high RH reading. The first is the presence of conductive dust particles or liquid which can get lodged in the humidity sensing film. To protect against this, it is recommended to use the factory-installed ePTFE cover. The second and third sources of high RH readings is exposure to organic solvents and high temperature, high humidity environments. The sensor can recover from this through a rehydration cycle, please reference AN607 for details on the procedure.