Incorrect oxygen sensor

The incubator in my lab is currently displaying an oxygen reading of about 7.5%. However, I did a dissolved oxygen test by incubating a dish of PBS for a day and using a test kit and conversion spreadsheet, and I got that the ambient oxygen is closer to 18%, which is what the device should be at. My cultures are not showing any adverse effects, so I believe the oxygen sensor is incorrect.

Is there a way I can reset the sensor or would it have to be replaced?