Grove - Multichannel Gas Sensor v2 - abnormal values

Hi everyone, I bought 2 Multigas V2 sensors and when I connect them to my esp through I2C I always get the same values.
NO2 = 1023
CO = 1023
C2H5OH = 1023
VOC = 1023.

Then I would like to know what is possible to measure with this sensor in addition to these 4 gases.