Various examples are directed to systems and methods for operating an analyte sensor system using sensor electronics. An example method may comprise applying a bias voltage change to an analyte sensor bias voltage and measuring a current value for each of a plurality of time periods after application of the bias voltage change. The example method may also comprise determining an estimated impedance using the current values for the plurality of time periods and determining a characteristic of the analyte sensor using the estimated impedance. The example method may further comprise receiving from the analyte sensor a signal indicative of an analyte concentration, and determining an estimated analyte concentration level using the determined characteristic of the analyte sensor and the received signal.