Sensor readings are negative (-) or zero

Check for proper wiring of the LI-190R-BL: (see Using the LI-190R-BL Quantum Sensor), 2290 Millivolt Adapter (see Connecting the 2290 Millivolt Adapter), or LI-190R-SMV (see LI-190R-SMV or LI-191R-SMV Quantum Sensor).

Make sure the proper sign was used on the multiplier entered into the LI-1500, LI‑1400, or LI-250A, or other recording device (Calibration Constants and Multipliers). If the number is entered without the negative sign, readings will be zero in the LI-1500 and negative in the LI‑1400 and LI-250A.

Sensor readings are incorrect

Make sure the meter or logger is properly configured, including entering the sensor's correct calibration multiplier. Note that multipliers are different from the calibration constant, and there are different multipliers for use with millivolt adapters (see Calibration Constants and Multipliers).

Check the sensor's most recent calibration. Calibration certificates are available at Enter the sensor's serial number in the calibration data search box. Certificates include multipliers and the calibration date. We recommend factory recalibration for radiation sensors every two years (Factory Recalibration).

Check for loose cable connections. Moisture on connections can also cause erroneous readings. Check the sensor cable for damage, including nicks, cuts, or sharp bends.

Contact us ( if you are unable to resolve the issue.