I have a DS18B20 temperature sensor connected to a Raspberry Pi 3b+. I created a simple Python program to monitor the temperature of my heating system. The program works very well....when it works...sometimes it stops and when I check the raspberry pi, the sensor in /sys/bus/w1/devices is no longer there.
I noticed that the voltage between DQ and GND, when the sensor is correctly detected by the raspberry, is equal to 5V, while when it is not detected, the voltage drops to 1.3V. it's the only strange thing I've noticed and it persists even when changing raspberry and changing probe. I even changed the cable.
I have other 3 systems like this one that works perfeclty with the same configuration.
On the raspberry I use a board, this board https://sferalabs.cc/product/iono-pi-board/