Apparatus and methods are operative to probe the condition of a sensor either initially, at any point thereafter or continuously during a continuous sensor operation for measuring an analyte in a bodily fluid (such as performed by, e.g., a continuous glucose monitoring (CGM) sensor). Results of the probe may include calibration indices determined from electrical signals obtained during the probe. The calibration indices may indicate whether in-situ adjustment of the sensor's calibration should be performed either initially and/or at random check points. Probing potential modulation parameters also may be used during analyte calculations to reduce the effects of lot-to-lot sensitivity variations, sensitivity drift during monitoring, temperature, interferents, and/or the like. Other aspects are disclosed.