Grove Temperature & Humidity Sensor - inaccurate readings


I have 2 of the TH02-based Grove Temperature & Humidity sensors (SKU: 101020074). Both of them return inaccurate readings: the temperature is about 3C too low, and the humidity is about 20% too high. The readings aren’t random - they rise and fall correctly, but are consistently off the correct value.

I’m using the sample Arduino code from the Wiki.

Is anyone else seeing this behaviour? Any ideas what might be causing it?



An update to my earlier post…

I received a 3rd unit in the mail today, and this one works correctly. Same Arduino, same code. Visually comparing the 2 sensor units, good and bad, doesn’t show any differences. No missing components, no components appear to be soldered incorrectly.

Does anybody have an idea on what might be wrong with the 2 bad units, or what sort of test I can run to pinpoint the problem? If it’s just a matter of resoldering something, I can likely fix it myself.



how are you determining the readings are incorrect? Is there a way to log the data?

I was initially comparing the temperature and humidity readings to those from an off-the-shelf meter. When I received the 3rd Grove sensor, I compared the readings from the 1st 2 sensors I bought to the 3rd one. The 3rd Grove sensor and the off-the-shelf meter more-or-less agree (less than 1C difference in temperature), while the other 2 sensors report temperatures that are about 3C lower.

I haven’t tried logging the data. I guess you’re wondering if the first 2 sensors are consistently wrong? I’ve watched them report readings every 5 seconds for several minutes, and they are consistent over that period - each reading returns about the same temperature and humidity (less than 0.5 variance), but the temperature’s low and the humidity’s high.