Hello @microdynasty I think in UIFlow, when a unit is added, part of the internal initialization, e.g. what's happening when below line is executed, is to check for the two sensors in the ENV III unit, which in your case results in the I2C error. env20 = unit.get(unit.ENV2, unit.PORTA) Hmm, I can see what you mean about ENV III being compatible, but I wonder if M5Stack meant after ENV III has been added in UIFlow? Sorry, I don't know enough about MicroPython to help you, but maybe have a look at the Arduino example to get an idea about the I2C commands required to read data from that sensor? Good luck! Thanks Felix