Gasoline Particulate Filter (GPF) OBD Monitoring Requirements

This paper presents the collaborative efforts of the USCAR GPF OBD Working Group to evaluate and recommend On-Board Diagnostic (OBD) monitoring requirements for Gasoline Particulate Filters (GPFs). The group, comprising of representatives from major US OEMs, aims to establish a unified understanding of GPF monitoring capabilities and propose regulatory recommendations to CARB. The paper explains how the physics of soot generation and soot burning determine GPF operating strategies and the applicability of proposed OBD monitors. Since there was no section in the OBD regulation for GPFs, the "group" started with Monitoring Requirements for Diesel/Compression-Ignition Engines section on Diesel particulate filter regulations and evaluated their relevance and applicability to GPFs. This effort furthermore motivates the regulatory interpretations, and diagnostic strategies, culminating in a proposed framework for GPF OBD compliance.