Patent ID: 7628063
Filing Date: 2009-12-08
Classification: F01N,Y02T

Abstract:
1. A method for on-board diagnostics of diesel engine NOx adsorber catalysts that trap NOx in exhaust gases during the typical lean exhaust gas condition and that are periodically regenerated by enriching the exhaust gas by introducing one or more reductants into the exhaust gas, comprising the steps of a. providing a first lambda sensor in the exhaust gas upstream of the NOx adsorber catalyst and a second lambda sensor in the exhaust gas downstream of the NOx adsorber catalyst, and b. correlating on-board a difference in the signal outputs from the first and second lambda sensors when the NOx adsorber catalyst is being regenerated by enriching the exhaust gas with one or more reductants with the diagnostic conclusion that the NOx adsorber catalyst remains operable to remove NOx from the exhaust gas in the lean exhaust gas condition; and correlating on-board a lack of difference in the signal outputs from the first and second lambda sensors when the NOx adsorber catalyst is being regenerated by enriching the exhaust gas with one or more reductants with the diagnostic conclusion that the NOx adsorber catalyst has become inoperable to remove NOx from the exhaust gas in the lean exhaust gas condition.