Method and system for diagnostics of a particulate matter sensor

ABSTRACT OF THE DISCLOSURE A diagnostic method and system is described for diagnosing an operating condition of a conductive particulate matter sensor (10, 210). The sensor has a substrate (30) and two electrodes (34, 36) on the substrate adapted to collect particulate matter between the electrodes, thereby establishing an electrically conductive path through collected particulate matter between the electrodes that can be detected by measuring electrical resistance between the electrodes, R elect . The diagnosis is performed by detecting whether water vapor condensate may be present between the electrodes and if it is, then measuring resistance between the electrodes while subjecting the sensor to conditions sufficient to evaporate any water vapor condensate and diagnosing a validation that the sensor is in proper operating condition if resistance increases in a manner consistent with evaporation of condensate.