I just received two AirGradient One Pro v1 presoldered.
So far I’m lucky about how they work, thank you.
There is just one flaw. The NOx readings on both devices are always of the value one.
I checked that the sensor is pointing outwards but I have no clue what’s going wrong here.
That is likely correct. The VOC and NOx values are an index, not a measure of an actual value.
When the device boots up, it gets a baseline and then VOC 100 means there is no change. If it goes lower, the VOC levels reduced and if it goes higher then the VOC levels increased.
NOx is also an index that starts at 1 when it boots up and if it increases, then it is measuring an increase in NOx levels. So staying at 1 means it is not detecting any increase from when you powered it up.
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Adding to @MallocArray that the NOx sensor seems not to be extremely sensitive. So it needs higher concentrations to be triggered.
More information about the index: