Pressure sensor (LPS25HB) error in sensing

Good day,

I am an engineer testing the LPS25HB pressure sensor in a wind tunnel.
I have attached a graph of the pressure sensed over time.
Because I am testing on an aerofoil I should be getting a negative relative pressure to atmosphere.
I do achieve this negative relative pressure. The error arises when letting the wind tunnel run at steady state the pressure sensor does not remain at a constant negative relative pressure. The readings start to drift up wards for some reason. It is also observed that when I turn the wind tunnel off the pressure sensor does not climb then upwards. It remains at the height (Assuming a new atmospheric pressure for some reason)pressuevstime

It looks like the pressure sensor is loosing its internal reference pressure? If you have any help with this please share.
I also observed a constant drift in the sensor that is not normal. Any idea why this could be?

Thanks in advance


I assume you are working with this product:

What do you have the sensor connected to? Also what code are you running?

Thank you,
Travis Elliott