A method for verifying the validity of an output of a particulate matter sensor mounted in an engine exhaust system downstream of a diesel particulate filter, the particulate matter sensor including a pair of electrodes spaced apart from each other, includes initiating regeneration of the diesel particulate filter, applying and maintaining a higher than nominal voltage across the electrodes following the step of initiating regeneration of the diesel particulate filter, and measuring an electrical parameter across the electrodes while the higher voltage is applied across the electrodes, where the electrical parameter is indicative of an amount of soot accumulated on the sensor. The reading of accumulated soot is evaluated to determine whether the sensor is indicating that the amount of accumulated soot is within an expected range based on a clean diesel particulate filter and the elevated applied voltage.