Hi Manmohan,
Usually, we do not recommend routing wires on the bottom layer corresponding to the BME280 solder pad. This area needs to be cleared and copper should not be laid. The wiring with high current needs to be far from BME280. The BME280 itself also needs to be kept away from heat sources.
What are your heat sourcing elements? What is the maximum ambient temperature that they may experience while working? How far is the heat sourcing elements from BME280?
Additionally, when the heat sourcing elements are not working, i.e. not heating, what are the temperature, humidity, and air pressure of the BME280 on the 4 boards?
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