Go Direct^® CO₂ Gas Sensor (GDX-CO2)
Specifications and User Guide

TROUBLESHOOTING
Note: These instructions are for the Go Direct CO2 Gas Sensor. For information regarding the CO₂ Gas Sensor (CO2-BTA), see CO₂ Gas Sensor Troubleshooting and FAQs

-Primary Test: Start the software and identify your sensor, if necessary. Let the sensor warm up for at least 180 seconds before continuing. Blow directly on the shaft of the sensor. You should see an increase in CO2 levels.

-Secondary Test: If the CO2 Gas Sensor is not giving reasonable readings in the Primary Test, try calibrating it. This should ideally be done outside in fresh air (which should be close to 400 ppm).

Calibration

Fill the 250 mL Nalgene bottle to the brim with water, take it outside, and dump the water to ensure it is then filled with fresh air. While still outdoors, insert the sensor into the bottle that now contains fresh outside air. Take the bottle and sensor to where the calibration will be done.
Start the software and connect your sensor. Let the sensor warm up for at least 180 seconds before continuing.
When the sensor has warmed up (readings should have stabilized), calibrate the sensor using a one-point calibration. Enter a value of 400 ppm for the sample of air collected. Once finished, the sensor should read very close to 400 ppm.

BATTERY TROUBLESHOOTING
If the sensor can be turned on when connected by USB but not when disconnected from USB, it is likely that the battery just needs to be charged. In this case, charge the sensor for several hours and try again. If, however, the sensor won’t turn on regardless of whether the USB cable is connected or not, and you are confident that the USB cable is good by having tested it on another sensor, then the battery has likely reached its end of life and can no longer hold a charge. In this state, the sensor cannot be used even if connected by USB, so the battery will need to be replaced. The rechargeable battery in this sensor is covered by a one year warranty but should last two to five years in typical use. Note that if the battery is less than one year old and the sensor cannot be turned on even when connected by a working USB cable, another possibility is that the USB port is bad. In this case, contact Vernier technical support for assistance. 

How do I replace the battery in a Go Direct Wand-Type Sensor?