Automotive applications equipped with Diesel engines are subject to stringent legislative requirements in terms of particulate matter (PM) emissions. A Diesel particulate filter (DPF) reduces the tailpipe PM content in the exhaust gas to fulfill the emission thresholds of law's authority. As an emission relevant component, the DPF efficiency must be monitored according to the on-board diagnostic (OBD) regulation. In the US and European market, these OBD regulation limits are becoming more tightened.Currently established methods rely on the analysis of the differential pressure sensor signal across DPF. The measured pressure loss depends on a lot of disturbance variables. Thus, monitoring concepts based on differential pressure become increasingly difficult to comply with future OBD legislation.New developed PM sensors offer the possibility to detect and quantify the particulate emissions in DPF downstream position. This information can be processed in a DPF efficiency OBD monitor.This paper presents a PM sensor based algorithm for OBD of particulate filter efficiency. The optimization of the concept is shown by means of engine bench measurements. Validation results from vehicle tests explain the behavior of the monitoring concept.