capacitive soil moisture sensor with wrong data

[Koenig]

Problem with capacitive soil moisture sensor (https://www.ebay.de/itm/Kapazitiver-Ana ... ensor-TFZ/): I calibrated this perfectly (once completely dry and once under water ). However, he always returns completely wrong numbers, sometimes in the minus range. The supply cable is about 2 meters long. The moisture meter is connected via ADS1115. Another, identical device is working properly. Is there a trick, maybe with a resistance?

[TD-er]

The URL doesn't work.
Could it be the sensor has been damaged?
So maybe water can get more close to the capacitive part of the sensor?
The way I think these sensors work, then distance to the (wet) soil is key to the measured value.

[Koenig]

Here is a new url: https://go.twenga.de/to?s=5338647&gap=1 ... gIRivD_BwE
But the sensor works quite well if i test it in a dry and totally wet environment. Today for example the values are totally normal. But some days the values are getting crazy

[werner_g]

I made the same experience with that sensor and also with ADS1115. Works perfectly in rooms, but when installing outdoor I could not get any reliable datas. Really a pity! Maybe temperature and air humidity is responsible for this.