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[TGS4161] Improving the CO2 Accuracy
This post will cover tips and tricks required to make the TGS4161 work more consistently. This was the original CO2 Monitor that i had made (with 6 LEDs and optionally Display and WiFi)

The TGS4161 is an electrochemical sensor that is said to deliver +/- 20% accuracy of CO2 Concentration.

While this may be true, time has shown that there are several important things to keep in mind, due to the fact that it is electrochemical and some things change over time.

1. If the sensor is powered on and disconnected only for short (<5-10 minute) periods of time it works quite well.
2. Once the sensor is disconnected for a longer period of time - two things happen

   2.1. It starts thinking CO2 is more than it actually is (this may be even with more than 3000 ppm). To fix this a couple of things can be done
         - (automatic) ensure latest FW is used (see below on upgrading to latest fw). The earlier firmwares did autocalibration each 10 days, the new one does it each 3 days
         - (manual) via the vThings Configuration Utility (see below) press the button in Settings -> Reset Calibration. Then the calibration cycle will start again and it will adjust to the lowest CO2 level faced (if it is not too cold outside <10 degrees C, you can put it there for 15 minutes)

  2.2. It starts thinking CO2 is less than it is. E.g. it is 2000 ppm in the room but it shows 1000
         - calibrating the top level cannot be done automatically. This is why the solution is to issue a special command from the config tool, put the sensor in a plastic bag, exhale your breath in it. And leave it like this for 10 minutes. The sensor measures up to 15,000 ppm, and we exhale 50k+, so this will do it. This is not yet part of the firmware. Please subscribe to this topic to get update about it.

Once those two procedures are done - the sensor will again show reliable data, until the next time it is turned off. I believe at some point of time after a a number of restarts, this will settle, but i haven't done measurements for this

Checking firmware version
Follow the steps as described here Once the config tool starts it will show the version in the first line in the output.

Latest version is: 1.11

Updating to latest firmware version
  1. Download the XLoader tool from here

  2. Download the latest firmware from here:, and unzip it. Make sure to download the correct file. _tgs - this is for the original and cheaper sensor with the less accurate sensor (TGS4161), _ndir - this is for the more accurate IR-based sensor. Flashing the wrong one will not brick the device - it will simply display wrong values

  3. Configure the tool like this (by adding the correct port):
  4. [Image: XLoader.PNG]

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