NOx adsorber diagnostics and automotive exhaust control system utilizing the same

A process for controlling an exhaust system for an internal combustion engine, comprising:

• flowing exhaust gas from the engine past a first oxygen sensor, through a NOx adsorber, past a second oxygen sensor, through a catalyst and past a third oxygen sensor, wherein the first oxygen sensor, the second oxygen sensor, and the third oxygen sensor, are in operable communication with an electronic control module;
• using a switching delay between the first oxygen sensor and the second oxygen sensor to determine a NOx value, wherein the NOx value is selected from the group consisting of a NOx regeneration time, a stored NOx amount, a NOx storage efficiency, and combinations comprising at least one of the foregoing NOx values;
• and
• initiating a desulfurization process when the NOx value is less than or equal to a first selected value, wherein the desulfurization process comprises
• increasing a temperature in the exhaust gas to a desulfurization temperature;
• switching the engine operation from a normal combustion condition to a rich combustion condition to produce a rich exhaust gas;
• monitoring the rich exhaust gas exiting the catalyst;
• and
• providing oxygen to the catalyst when, during the desulfurization process, the third oxygen sensor signals a third condition rich of stoichiometry.