Code not working on Heltec WiFi LoRa V3 board, even when powered with 5V

[JuliaSteiwer]

Hello, I am using your EC (K=1) sensor with a Heltec board, and to ensure that the sensor gets 5V input voltage, I power the sensor with a battery instead of using the pins of the Heltec board.

I have noticed that the code fr calculating the EC value only returns 0.00 on this board, while it works fine on the Arduino Uno. Is there any way I can get this code to work on the Heltec board?

Thank you already in advance for your reply.