MH-Z19 CO2 Sensor

The MH-Z19 is a small non-dispersive infrared sensor that can measure CO2 level. High CO2 levels can lead to drowsiness, poor concentration, loss of attention or increased heart rate. The CO2 level outside is around 400ppm, but inside levels can reach between 1000 and 5000 ppm. High CO2 levels indicate that you should increase ventilation.

Check out the Open Home Automation web site for a quick guide how to connect the sensor to your PC or Raspberry Pi.


To use this sensor in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
  - platform: mhz19
    serial_device: /dev/tty.SLAB_USBtoUART
  • serial_device (Required): The serial port to use. On *nix systems, it can often be identified by $ ls /dev/tty*
  • name (Optional): The name displayed in the frontend.
  • monitored_conditions (Optional, starting from version 0.40): Conditions to monitor. Supported conditions:
    • co2 (default)
    • temperature

Full example:

  - platform: mhz19
    serial_device: /dev/tty.SLAB_USBtoUART
    name: My MHZ19
      - co2
      - temperature