Enviro+ humidity wrong values

I bought a Enviro+ from Elektor International Media BV.

All reading values are good, except humidity. The values are always below 30%, right now 20% by raining weather, right value might be above 50 to 60%
You can see my recordings on https://opensensemap.org/explore/5dadfecc203db9001a12f50e.

I wrote to Elektor, but they ask me to contact you :

> Cindy Tijssen (Customer Services (EN)) 8 nov. 2019 09:55
**> **
> Cher Monsieur Arbel,
**> **
> Nous avons eu une réaction du fournisseur, voir ci-dessous :
**> **
> could you ask him to post on our forums so that we can support him directly?
> https://forums.pimoroni.com/

Thank’s a lot for your quick answer.

Do you have a fan cooling the board? If not the RPI heats the board and that causes the humidity to drop.

Even with a fan keeping it ambient it reads nearly 10% less than my cheap Chinese hygrometers. Not sure which is correct. My garage at 12C currently shows 50% in a very wet UK climate.

I had issues with heat from the Pi’s SOC messing with the sensors on my Sense Hats. Temperature read high and humidity low. Especially if the Sense Hat was in a case, even a well ventilated case.
I put a Proto Hat between my Pi and Sense Hat and it helped a lot. Readings were pretty well normal again.
A proto zero

with an 11mm stacking header

may help. If that is your issue and its not a faulty sensor.