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CO₂ sensor Forum Discussions

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So I have been collecting data for about 6 days on two Sensor2Go PAS CO2 boards connected to a couple of Adafruit Feather Boards. Both have been successfully recording readings continuously on 10-second intervals for that time period, with the values in the range I expected.

Out of nowhere, at a time when no one was around and no substantial changes occurred to either the microcontroller/sensor setup or the environment the sensor is in, the value coming from the sensor changed drastically. In a matter of 3 readings(20 seconds), the value went from 1176->1441->2527. 1176 is the expected and correct value at that time. This was in an empty office with a closed door and a continuously decreasing value as no one was around and it was after work hours. The values have continued to stay in this range(ppm>2000) since this occurred, although changing like it is reacting to the CO2 values in the air. I have included a screenshot to show the data change on a graph. 


  • Adafruit Huzzah32 Feather
  • PAS CO2 Shield2Go
  • Arduino Code+PasCo2 Library
  • Reading using Continuous Mode

Debugging Attempts:

  • Feather reset
  • Feather program reflash
  • Shield2Go power reset
  • Shield2Go placed in ambient, outdoor air
  • Shield2Go disconnected and placed in ambient, outdoor air

I verified that the reading was incorrect by using an additional CO2 sensor set up directly next to the incorrectly reading sensor. The other sensor detected values within the range of expectation.

I am looking for thoughts on why this may be occurring. Again, it was reading completely fine for multiple days and seemingly at random started reading incorrectly. 


1 Reply
50 solutions authored 25 likes received 5 likes given

Hi @cmw,

This is not an expected behavior.

Could you please perform a forced compensation and check again?

Please let me know the result.

Refer to Design Guidelines document to understand more about implementation of the sensor and preventive measures.

Thanks and regards,