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John WilliamsJul 26, 2025
How to fix YSI Measuring Instruments when the instrument will not calibrate?
- EEric RobbinsJul 26, 2025
If your YSI Measuring Instruments will not calibrate and displays “Calibration Over”, “Calibration Under”, or “Unstable Reading” during calibration, verify the barometer reading and the correct sensor and membrane type selection in the System Setup menu. Ensure the calibration sleeve is 100% water saturated by moistening the sponge. If performing mg/L or ppm calibration, ensure adequate sample movement. Allow sufficient stabilization time for dissolved oxygen and temperature. Wait at least 3 seconds before confirming a DO % or DO %Local calibration. Replace the membrane and electrolyte and clean the sensor electrodes. If the issue persists, return the system for service.