The CO₂ LED is available only on the TX T&H CO2 transmitter 600-053 .
By enabling this feature, the device’s front LED will blink according to the measured CO₂ levels, based on the thresholds you have defined.( CO2 LED behavior )
Before configuring the CO₂ alarm thresholds, it is essential to enable the LED via a downlink as shown in the link below: [LoRaWAN] LoRaWAN Data frames decoding and downlink generator
Please note that if the LED is not enabled, the configured alarm thresholds will not be processed by the transmitter.