ESPHome SEN66 update using the built-in sen6x component

README.md

SEN66 update for ESPHome 2026.7

The previous configuration used uELKO/esphome_external_components, which no longer compiles because ESPHome 2026.7 removed an API it depended on.

The updated configuration:

• Uses ESPHome's built-in sen6x component.
• Correctly treats PM1, PM2.5, PM4 and PM10 as cumulative values.
• Removes the custom PM10 sum and unreliable custom IAQ calculation.
• Keeps TVOC and CAQI explicitly labelled as estimates.
• Stores API and OTA credentials in secrets.yaml.

Tested successfully with ESPHome 2026.7.3 on a Seeed XIAO ESP32-C6 and Sensirion SEN66.

The -4.5 °C temperature offset and +12% humidity offset in the configuration are specific to our enclosure and should be recalibrated for another build.

air-quality-sensor.yaml

esphome:
  name: air-quality-sensor
  friendly_name: Air Quality Sensor
  min_version: "2026.7.3"

esp32:
  board: seeed_xiao_esp32c6
  framework:
    type: esp-idf

i2c:
  sda: GPIO22
  scl: GPIO23
  scan: false

sensor:
  - platform: sen6x
    id: sen66
    type: SEN66
    pm_1_0:
      name: "PM <1 µm"
      id: sen66_pm_1_0
      accuracy_decimals: 1
    pm_2_5:
      name: "PM ≤2.5 µm"
      id: sen66_pm_2_5
      accuracy_decimals: 1
    pm_4_0:
      name: "PM ≤4 µm"
      id: sen66_pm_4_0
      accuracy_decimals: 1
    pm_10_0:
      name: "PM ≤10 µm"
      id: sen66_pm_10_0
      accuracy_decimals: 1
    co2:
      name: "CO₂"
      id: sen66_co2
      accuracy_decimals: 0
    temperature:
      name: "Temperature"
      accuracy_decimals: 1
      id: sen66_temperature_top
    humidity:
      name: "Humidity"
      accuracy_decimals: 0
      id: sen66_humidity
    voc:
      name: "VOC Index"
      id: sen66_voc_index
      filters:
        - sliding_window_moving_average:
            window_size: 9
            send_every: 1
    nox:
      name: "NOx Index"
      id: sen66_nox_index
      filters:
        - sliding_window_moving_average:
            window_size: 9
            send_every: 1
    update_interval: 10s

  - platform: template
    name: "Ambient Temperature"
    id: sen66_ambient_temperature
    unit_of_measurement: "°C"
    accuracy_decimals: 1
    device_class: temperature
    state_class: measurement
    update_interval: 10s
    lambda: |-
      return id(sen66_temperature_top).state + id(temperature_offset_input).state;

  - platform: template
    name: "Ambient Humidity"
    id: sen66_ambient_humidity
    unit_of_measurement: "%"
    accuracy_decimals: 0
    device_class: humidity
    state_class: measurement
    update_interval: 10s
    lambda: |-
      return id(sen66_humidity).state + id(humidity_offset_input).state;

  - platform: template
    name: "Estimated TVOC Molhave Equivalent"
    id: sen66_estimated_tvoc_molhave
    unit_of_measurement: "mg/m³"
    accuracy_decimals: 2
    device_class: volatile_organic_compounds
    state_class: measurement
    update_interval: 10s
    lambda: |-
      const float voc_index = id(sen66_voc_index).state;
      if (isnan(voc_index) || voc_index < 1.0f || voc_index >= 501.0f) {
        return NAN;
      }
      return ((log(501 - voc_index) - 6.24) * (-996.94)) * 0.001;

  - platform: aqi
    name: "PM CAQI Estimate"
    id: sen66_pm_caqi_estimate
    pm_2_5: sen66_pm_2_5
    pm_10_0: sen66_pm_10_0
    calculation_type: CAQI
    accuracy_decimals: 0
    state_class: measurement

number:
  - platform: template
    name: "Temperature Offset"
    id: temperature_offset_input
    optimistic: true
    min_value: -10.0
    max_value: 10.0
    step: 0.05
    initial_value: -4.5
    restore_value: true
    unit_of_measurement: "°C"
    entity_category: config
    mode: box

  - platform: template
    name: "Humidity Offset"
    id: humidity_offset_input
    optimistic: true
    min_value: -20.0
    max_value: 20.0
    step: 1
    initial_value: 12.0
    restore_value: true
    unit_of_measurement: "%"
    entity_category: config
    mode: box

logger:
  level: INFO

api:
  encryption:
    key: !secret air_quality_sensor_api_encryption_key

ota:
  - platform: esphome
    password: !secret air_quality_sensor_ota_password

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password