Abstract: A method for operating an internal combustion engine (100) and exhaust system therefor includes the step of initiating a regeneration event in a diesel particulate filter (DPF 109) (401). A first oxygen concentration (213) of a gas upstream of the DPF 109, and a second oxygen concentration (215) of the gas downstream of the DPF 109 are sensed (403) to infer a rate of combustion of material in the DPF (405) based on the difference between the first (213) and the second (215) oxygen concentrations. The rate of combustion is compared to a threshold value (409) and the regeneration event in the DPF 109 is terminated (411) if the rate of combustion is above the threshold.

Abstract: De-sulfurizing a NOx adsorber catalyst (48) without significantly increasing the temperature of exhaust gases leaving the engine exhaust manifold (42) by using a diesel oxidation catalyst (46) between the exhaust manifold and the NOx adsorber catalyst to elevate exhaust gas temperature entering the NOx adsorber catalyst to suitable de-sulfurizing temperature through control of certain aspects of engine operation (24, 28, 52).