Last Updated or created 2026-07-17

Today I got, amongst other goodies a new CO2 sensor in the mail.

This is a MH-Z19C CO2/Temperature sensor.
(Easy to implement with ESPHome)

My dashboard. NOTE: Not calibrated yet!

YAML Code

# Board: Wemos D1 Mini (ESP8266) (Wemos)
# Definition: definitions/boards/d1_mini/manifest.yaml

esphome:
  name: newco2
  friendly_name: NewCO2

esp8266:
  board: d1_mini

logger:

api:
  encryption:
    key: "c/vSFcxi1YgYlXtvsjk4lFxxxxxxxxxxxxxxx="

ota:
  - platform: esphome

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:
    ssid: NewCO2 Fallback Hotspot
    password: "tepe9xxxxxxxxx"

captive_portal:

uart:
  - baud_rate: 9600
    rx_pin: 4
    tx_pin: 5
    id: uart_1

sensor:
  - platform: mhz19
    uart_id: uart_1
    co2:
      id: sensor_mhz19_1_co2
      name: CO2
    temperature:
      id: sensor_mhz19_1_temperature
      name: Temperature
    id: sensor_mhz19_1
    automatic_baseline_calibration: true
    detection_range: "5000ppm"
    
switch:
  - platform: template
    name: "MH-Z19 ABC"
    optimistic: true
    on_turn_on:
      mhz19.abc_enable: sensor_mhz19_1
    on_turn_off:
      mhz19.abc_disable: sensor_mhz19_1