SEN6x Series Environmental Sensor

The sen6x sensor platform allows you to use your Sensirion SEN62, SEN63C, SEN65, SEN66, SEN68 and SEN69C Environmental sensor (datasheet) sensors with ESPHome.

The I²C Bus is required to be set up in your configuration for this sensor to work.

Sensor	PM	RH/T	VOC	NOx	CO₂	HCHO
SEN62	✓	✓
SEN63C	✓	✓			✓
SEN65	✓	✓	✓	✓
SEN66	✓	✓	✓	✓	✓
SEN68	✓	✓	✓	✓		✓
SEN69C	✓	✓	✓	✓	✓	✓

# Example configuration entry
sensor:
  - platform: sen6x
    id: my_sen6x
    type: SEN69C
    pm_1_0:
      name: PM <1µm Weight concentration
    pm_2_5:
      name: PM <2.5µm Weight concentration
    pm_4_0:
      name: PM <4µm Weight concentration
    pm_10_0:
      name: PM <10µm Weight concentration
    temperature:
      name: Temperature
    humidity:
      name: Humidity
    voc_index:
      name: VOC Index
    nox_index:
      name: NOx Index
    co2:
      name: Carbon Dioxide
    formaldehyde:
      name: Formaldehyde

NOTE

The voc and nox keys were renamed to voc_index and nox_index, since these sensors report Sensirion’s unitless Gas Index rather than a concentration. The old keys still work but are deprecated and will be removed in ESPHome 2027.2.0.

Configuration variables

• type (Optional): The type of sensor. If not specified, sensor type will be auto-detected. If specified, the value will override auto-detection. In case of mismatch, a warning will be provided in the log.

  • SEN62
  • SEN63C
  • SEN65
  • SEN66
  • SEN68
  • SEN69C

• pm_1_0 (Optional): The information for the Weight Concentration sensor for fine particles up to 1μm. Readings in µg/m³.

  • All options from Sensor.

• pm_2_5 (Optional): The information for the Weight Concentration sensor for fine particles up to 2.5μm. Readings in µg/m³.

  • All options from Sensor.

• pm_4_0 (Optional): The information for the Weight Concentration sensor for coarse particles up to 4μm. Readings in µg/m³.

  • All options from Sensor.

• pm_10_0 (Optional): The information for the Weight Concentration sensor for coarse particles up to 10μm. Readings in µg/m³.

  • All options from Sensor.

• pmc_0_5 (Optional): The information for the Number Concentration sensor for ultrafine particles up to 0.5μm. Readings in particles/cm³.

  • All options from Sensor.

• pmc_1_0 (Optional): The information for the Number Concentration sensor for fine particles up to 1μm. Readings in particles/cm³.

  • All options from Sensor.

• pmc_2_5 (Optional): The information for the Number Concentration sensor for fine particles up to 2.5μm. Readings in particles/cm³.

  • All options from Sensor.

• pmc_4_0 (Optional): The information for the Number Concentration sensor for coarse particles up to 4μm. Readings in particles/cm³.

  • All options from Sensor.

• pmc_10_0 (Optional): The information for the Number Concentration sensor for coarse particles up to 10μm. Readings in particles/cm³.

  • All options from Sensor.

• temperature (Optional): Temperature.

  • All options from Sensor.

• humidity (Optional): Relative Humidity.

  • All options from Sensor.

• voc_index (Optional): VOC Index. Note: only available with SEN65, SEN66, SEN68 or SEN69C. The sensor will be ignored on unsupported models.

  • algorithm_tuning (Optional): The VOC algorithm can be customized by tuning 6 different parameters. For more details see the SEN6x datasheet.

    • index_offset (Optional): VOC index representing typical (average) conditions. Allowed values are in range 1..250. The default value is 100.
    • learning_time_offset_hours (Optional): Time constant to estimate the VOC algorithm offset from the history in hours. Past events will be forgotten after about twice the learning time. Allowed values are in range 1..1000. The default value is 12 hours.
    • learning_time_gain_hours (Optional): Time constant to estimate the VOC algorithm gain from the history in hours. Past events will be forgotten after about twice the learning time. Allowed values are in range 1..1000. The default value is 12 hours.
    • gating_max_duration_minutes (Optional): Maximum duration of gating in minutes (freeze of estimator during high VOC index signal). Zero disables the gating. Allowed values are in range 0..3000. The default value is 180 minutes.
    • std_initial (Optional): Initial estimate for standard deviation. Lower value boosts events during initial learning period, but may result in larger device-to-device variations. Allowed values are in range 10..5000. The default value is 50.
    • gain_factor (Optional): Gain factor to amplify or to attenuate the VOC index output. Allowed values are in range 1..1000. The default value is 230.

  • All other options from Sensor.

• nox_index (Optional): NOx Index. Note: only available with SEN65, SEN66, SEN68 or SEN69C. The sensor will be ignored on unsupported models.

  • algorithm_tuning (Optional): The NOx algorithm can be customized by tuning 5 different parameters. For more details see the SEN6x datasheet. Unlike VOC, the NOx algorithm has no configurable std_initial; the device requires it to be 50 and ESPHome always sends that value.

    • index_offset (Optional): NOx index representing typical (average) conditions. Allowed values are in range 1..250. The default value is 1.
    • learning_time_offset_hours (Optional): Time constant to estimate the NOx algorithm offset from the history in hours. Past events will be forgotten after about twice the learning time. Allowed values are in range 1..1000. The default value is 12 hours.
    • learning_time_gain_hours (Optional): Time constant to estimate the NOx algorithm gain from the history in hours. Past events will be forgotten after about twice the learning time. Allowed values are in range 1..1000. The default value is 12 hours.
    • gating_max_duration_minutes (Optional): Maximum duration of gating in minutes (freeze of estimator during high NOx index signal). Zero disables the gating. Allowed values are in range 0..3000. The default value is 720 minutes.
    • gain_factor (Optional): Gain factor to amplify or to attenuate the NOx index output. Allowed values are in range 1..1000. The default value is 230.

  • All other options from Sensor.

• co2 (Optional): The carbon dioxide concentration in ppm. Note: only available with SEN63C, SEN66 or SEN69C. The sensor will be ignored on unsupported models.

  • automatic_self_calibration (Optional, boolean): Enable or disable the CO₂ sensor’s automatic self-calibration (ASC). The device enables ASC by default.
  • altitude_compensation (Optional, int): Altitude of the sensor location in meters above sea level, used to compensate the CO₂ reading. Allowed values are in range 0..3000. The device ignores it once an ambient pressure is written by either option below.
  • ambient_pressure_compensation (Optional, int): Static ambient pressure in hPa used to compensate the CO₂ reading. Allowed values are in range 700..1200.
  • ambient_pressure_compensation_source (Optional, ID): A pressure sensor (in hPa) whose value updates the ambient pressure compensation on every update cycle. Values outside 700..1200 hPa are ignored with a warning. Can be combined with ambient_pressure_compensation, which then applies until the source reports a valid value.
  • All other options from Sensor.

  Options that are not set are not written to the device.

• formaldehyde (Optional): The Formaldehyde (HCHO) concentration in ppb. Note: only available with SEN68 or SEN69C. The sensor will be ignored on unsupported models.

  • All options from Sensor.

• address (Optional, int): Manually specify the I²C address of the sensor. Defaults to 0x6B.

• update_interval (Optional, Time): The interval to check the sensor. Defaults to 60s.

NOTE

The sensor needs about a minute “warm-up”. The VOC and NOx gas index algorithm needs a number of samples before the values stabilize.

Binary Sensor

The sen6x binary sensor platform exposes the device status register as diagnostic entities. The register is read and cleared once per update cycle while measuring, so each error entity reports whether the problem occurred since the last update; fan_speed_warning shows the fan’s state at the moment of the read. The entities keep their last state while the measurement is stopped.

binary_sensor:
  - platform: sen6x
    fan_error:
      name: Fan Error
    fan_speed_warning:
      name: Fan Speed Warning
    rht_error:
      name: RH/T Error
    gas_error:
      name: Gas Error
    co2_error:
      name: CO2 Error
    hcho_error:
      name: HCHO Error
    pm_error:
      name: PM Error

Configuration variables

• sen6x_id (Optional, ID): The ID of the sen6x sensor component.
• fan_error (Optional): The fan is switched on but not spinning.
• fan_speed_warning (Optional): The fan speed is more than 10% off target. Not latched; clears by itself.
• rht_error (Optional): Error in the relative humidity and temperature sensor.
• gas_error (Optional): Error in the VOC/NOx gas sensor. Only available with SEN65, SEN66, SEN68 or SEN69C.
• co2_error (Optional): Error in the CO₂ sensor. Only available with SEN63C, SEN66 or SEN69C.
• hcho_error (Optional): Error in the formaldehyde sensor. Only available with SEN68 or SEN69C.
• pm_error (Optional): Error in the particulate matter sensor.

All entities support all options from Binary Sensor. Entities not supported by the detected model are ignored with an error in the log.

Actions

The measurement can be controlled and maintenance functions triggered from automations. On the SEN6x family, fan cleaning and the SHT heater only work while the measurement is stopped, and the device needs wait time after each command (1400 ms after stop, 10 s after fan cleaning, 20 s after the heater). Commands sent too early are ignored with a “Device busy” warning.

sen6x.start_measurement Action

Starts a continuous measurement. The warm-up period applies again before values are published. On SEN63C and SEN69C the measurement must not be restarted within 24 s of a start while the CO₂ sensor is conditioning; ESPHome enforces this.

sen6x.stop_measurement Action

Stops the measurement and puts the device in idle mode. No values are published while stopped.

sen6x.start_fan_cleaning Action

Runs the fan at maximum speed for 10 seconds to blow out accumulated dust. Only accepted in idle mode.

sen6x.activate_sht_heater Action

Activates the built-in heater of the RH/T sensor for 1 second with 200 mW to reverse creep at high humidity. Only accepted in idle mode.

# Example: fan cleaning via a button
button:
  - platform: template
    name: Fan Cleaning
    on_press:
      - sen6x.stop_measurement: my_sen6x
      - delay: 2s
      - sen6x.start_fan_cleaning: my_sen6x
      - delay: 11s
      - sen6x.start_measurement: my_sen6x

Wiring

The sensor has a JST GHR-06V-S 6 pin type connector, with a 1.25mm pitch. The cable needs this connector:

Pins 2 and 5 (GND) and pins 1 and 6 (VDD) are connected internally.

For better stability, the SDA and SCL lines require suitable pull-up resistors.

See Also

• Sensor Filters
• Sen5x Series Environmental sensor
• Absolute Humidity
• SDS011 Particulate Matter Sensor
• PMSX003 Particulate Matter Sensor
• CCS811 eCO_2 and Volatile Organic Compound Sensor
• SCD4X CO₂, Temperature and Relative Humidity Sensor
• SPS30 Particulate Matter Sensor
• SGP40 Volatile Organic Compound Sensor and SGP41 VOC and NOx Sensor
• API Reference: sen6x.h