but I couldn’t solve it. but in the meantime i upgraded from RPi 3 to RPI4. And there were also a lot of HA updates. so I don’t know if it works now. I’m not using it at the moment.
I can try a new implementation in the current environment and let you know. I just don’t have much time so please be patient
I’m having the exact same problem. A couple of upgrades back my MHZ19 suddenly stopped working (read timeout as above). Checked the cables, and the sensor responds from the command line. Used to run in in a pyenv (Hassbian) but recently upgraded hass.io ( Home Assistant 2021.2.3, 5.4.83-v7, 32 bit) with the same result. Have enableuart=1 in my config.txt and the /dev/serial0 I have previously used shows up as expected. But to no avail, hass.io still is unable to present any values and my log is filled with: