Technical feasibility of different regulatory OBD threshold limits (OTL) for Euro 6 (LD) vehicles : final report

For on-board diagnostics (OBD) requirements in the Euro 6 Light Duty vehicle legislation, the detection of emission reduction system failures against the particulate OBD threshold limits (OTL) is of major importance. The OBD thresholds set out in Commission Regulation (EC) 692/2008 and amended by Commission Regulation (EC) 459/2012 are subject to a review to be conducted by the Commission by 1 September 2014. This report describes a study performed by a consortium of LAT, Ricardo UK and TNO, that aims to support the technical feasibility assessment of "Final OTLs" for particulate matter (PM) and NOx for Euro 6 Light Duty diesel fuelled vehicles. In the study worldwide OBD requirements, certification procedures, test methods and technologies introduced by OEMs on latest vehicle models with focus on PM and NOx OTLs for Diesel vehicles were analysed. Further a desktop analysis to compare vehicle operation over the EU and US type approval driving cycles, in order to assess the relation between EU and worldwide OBD requirements was performed. Summarizing all findings of this study, it can be concluded that: · Besides the difference between US and EU legislation and type-approval procedures, the assessment revealed similarities in operation and OBD system performance and it was possible to draw a safe comparison path. · Existing technologies allow the implementation of OBD hardware and algorithms able to cope with the more stringent Euro 6 PM and NOx OBD requirements. · Results were derived for vehicles belonging to the high engine capacity diesel engines in Europe. · Cycle duration of the OBD demonstration type-approval cycle may be an issue for some vehicle manufacturers especially in the early stage of development. If deemed necessary the duration of the type-approval cycle may be extended to two consecutive non-stop driving cycles to allow more time for OBD monitor completion.