Hi, just received a touch sensor. The AQ/VOC measurement is fixed at 50. I’ve tried a sharpie and no response from the sensor. This is what is see from the BME. Any ideas before I RMA the unit?
BME680: 88.00°F RH: 43.00% Dew: 62.00°F P: 973.17 hPa AQ: 50.00 ADC: 0.41V
Quick update. After a while the BME68x did start to respond. I wonder if there is an initial stabilization period that I wasn’t letting complete (moving it around).
Hi @Bulgin
The VOC sensor takes about 48 hours to ‘burn in’. This will cause the sensor to read around the 50 mark for a bit. I generally do not rely on any data produced by the BME for at least 48 hours after first plugging in the device.
Hope this helps 
Are you sure about that? Is that what PurpleAir says? What about when moving locations (ie unplugging and plugging back in a few minutes later)? I have not seen it plateau at any number when moving it (I don’t recall when it was new if it did).
From my research the burn in period is only at first device usage out of the factory. This matches my experience.