Abstract: The present technology provides systems for monitoring particulate matter buildup on a filter installed in the engine exhaust stream of a vehicle. A filter differential pressure sensor monitors a pressure differential across the filter. A downstream differential pressure sensor monitors a pressure differential across an exhaust stream outlet. A processor monitors a particulate buildup value based at least in part on the pressure differential across the filter and the pressure differential across the exhaust stream outlet. A method for monitoring particulate buildup is also provided. The method monitors a pressure differential across the filter, and determines a downstream exhaust flow rate based on a pressure differential between a filter outlet housing and an exit pipe, where the diameter of the filter outlet housing is greater than the diameter of the exhaust exit pipe.