Validation

Are you referring to the Variable Wavelength Detector's grating motor test? If so, the motor, position sensor, or main board needs replacement, and this is best done by service personnel. Let me know if you'd like a quote for a repair.

If it's just the caffeine test that is failing due to the measured lambda-max, you can recalibrate the detector with water in the flow cell under the diagnostic test menu.

You can calibrate and correct the detector wavelength using inbuilt diagnostic tests (wavelength calibration). Note you should also evaluate what impact the incorrect wavelength may have had on results generated using this system.