You should be using the newer version, MH-Z19B, not MH-Z19.

The protocol is compatible though.

Also note they come in up-to-3000ppm and up-to-5000ppm variants. Be sure to get the latter.

In case it helps anyone: a very fast way to get it working and get graphs is to connect it to a Raspberry Pi running HomeAssistant. Takes a few clicks and 3 lines of config.