There are four main types of CO sensors. Only one has no false positives and I'm betting that it isn't the one Analox uses. My response was to Patti and it was from an electronic/electrochemical standpoint, not the simple steps the user follows to get the numbers to match. Analox has to work hard to shield the user from the pitfalls of CO sensing. I have formal degrees in both chemistry and electrical engineering and worked in analytical chemistry and voltammetry so I am slightly better than "absolutely no knowledge". I really hesitate to share this, but you asked.
I still question if they could afford to design for zero false positives, don't know, so I called it a guess. Please reread Patti's generous explanation and you will see why it is being discontinued. It is rare that one gets such an honest answer from industry.