Hi all — I’m building my first ESPHome air-quality monitors (CO2 / VOC / PM) and while researching I’ve been digging through threads in this category about confusing readings.
I’m putting together a troubleshooting guide built from real cases, not theory. So I’m asking: what’s the most confusing wrong reading your sensor ever gave you?
A few patterns I keep seeing in threads here:
- MH-Z19 stuck at exactly 400 ppm CO₂ for hours/days
- SGP40 VOC index behaving nothing like expected
- PMS5003 reading 0 while there’s obviously particles in the air
- BME680 gas readings that mean nothing for the first days
If you’ve got one, share:
- Sensor model + how it’s wired/placed (ESPHome, enclosure, room)
- What the reading did (a screenshot of the history graph is gold)
- What fixed it — or if you never figured it out
I’ll write up the collected cases as a guide and post it back in this category. Thanks!