Analysis of Evaporative and Exhaust-Related On-Board Diagnostic (OBD) Readiness Monitors and DTCs Using I/M and Roadside Data

• DOI: 10.4271/07-11-01-0001
• Publication Date: 2018-04-04T17:06:45Z
• Authors: Michael Sabisch; Meredith Weatherby; Sandeep Kishan; Carl Fulper
• Keywords: 0203 mechanical engineering; 13. Climate action; 11. Sustainability; 02 engineering and technology

Under contract to the EPA, Eastern Research Group analyzed light-duty vehicle OBD monitor readiness and diagnostic trouble codes (DTCs) using inspection maintenance (I/M) data from four states. Results roadside pullover emissions tests were also compared with same-vehicle I/M results one of Analysis focused on evaporative control (evap) system, catalytic converter (catalyst), exhaust gas recirculation (EGR) system oxygen sensor heater (O2 system). Evap catalyst monitors had similar overall rates (90% 95%), while EGR O2 systems higher (95% 98%). Approximately 0.7% 2.5% cycles a "ready" evap at least stored DTC, but DTC under 1% for systems, 1.1% in states enforced programs. Monitor decreased, increased, as vehicles aged. DTCs typically limited small subset all possible any particular system. For on-road versus analysis, lower occurred during test than test, prevalence was shown decrease around time vehicle's possibly indicating some positive influence reducing DTCs. Roadside Acceleration Simulation Mode (ASM) fail decreased suggesting programs emissions.