HI,
I'll try your serial interface code later.
It seems to be an accurate sensor, however - the values are a bit "bouncy". I'll incorporate a "running average" on the measurements - to calm it down.
I am always tempted to add more sensors to the nodes, but in this case it is not possible.
My casing design would not even allow for one additional resistor... ;-)

@alowhum. Yes it does. I've built a combined Co2, humidity and temp sensor using mh-z19 and dht22. it shows current values on an oled and reports back to openhab. will use a number of these for ventilation control.If anyone is interested I'll post the complete build when done (currently waiting for more components from China).