Hi, glad to be able to enjoy this community, I was reviewing the code and I don’t quite understand how I can use the CO2 sensor MH-Z19B. I’m quite beginner and I didn’t find any example in the library for this sensor.
Good day 
We currently don’t really support the MH-Z19. There was once a plan so there might be some code left overs in the library but it’s currently non-functional.