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Upcoming 2013 on-board diagnostic (OBD) requirements mandate that catalyzed diesel particulate filter (CDPF) nonmethane hydrocarbon (NMHC) oxidation efficiency degradation be monitored as the filter ages. The malfunction indicator lamp (MIL) is to light when exhaust NMHC levels are greater than two times the legal limit or when the CDPF has no detectable amount of NMHC conversion capability. In this study, a CDPF was thermoelectrically aged at 650°C from the degreened (near-new) to end of useful life (EUL) stage. CDPF total hydrocarbon (THC) oxidation efficiency was measured periodically using a suite of steady-state speed and load conditions ("snapshot test"). The snapshot test was performed after every seven hours of filter aging. Snapshot test data of steady-state THC oxidation efficiency change across the filter at the chosen operating conditions shows no discernible, consistent degradation as the filter is aged.

Upcoming California on-board diagnostics (OBD) regulations require lighting the malfunction indicator lamp (MIL) when a catalyzed diesel particulate filter (CDPF) is inert with respect to nonmethane hydrocarbon (NMHC). Light-off temperature shift detection uses a correlation between CDPF age and the gradual increase in catalyst light-off temperature to determine the age of a CDPF. The proposed OBD strategy necessitates slipping HC past the upstream diesel oxidation catalyst (DOC) to ignite on the CDPF. The best-case OBD solution space requires engine net power levels less than 43 hp on a Cummins ISB. Radial temperature measurements downstream of the DOC revealed regional DOC light-off which would not be able to be detected by a single temperature sensor. CDPF light-off independent of DOC light-off was never observed under any testing, eliminating the possibility of using light-off temperature shift as a detection strategy.