If the ODO is reading a negative value, follow the process to reset the calibration. How do I reset the calibration on the Optical DO Probe?

If resetting the calibration does not work and your Vernier Optical DO Probe (ODO-BTA) is was purchased before 2021, sadly it cannot be repaired.

If you are unsure of when it was purchased please contact Vernier Support and we will look into it for you.