A method for detecting catalyst deterioration in a vehicle includes executing a fuel-cut mode of an engine of the vehicle according to a operating state of the vehicle; calculating an oxygen storage capacity (OSC) of a catalyst using an oxygen sensor during the executing of the fuel-cut mode of the engine; and calculating catalyst deterioration based on the calculated OSC.

A method includes: initiating a low engine-out NOx (LEON) mode by controlling a component of a vehicle having an aftertreatment system to decrease an instantaneous engine-out NOx (EONOx) amount; comparing a temperature of the aftertreatment system during the LEON mode to a warm-operation threshold temperature; responsive to determining that the temperature of the aftertreatment system exceeds the warm-operation threshold temperature, disengaging the LEON mode; responsive to determining that the temperature of the aftertreatment system is below the warm-up operation threshold temperature, comparing information indicative of an operating status of the vehicle to a LEON exit threshold; and disengaging the LEON mode responsive to determining that the information indicative of the operating status of the vehicle during the LEON mode exceeds the LEON exit threshold.

Technical solutions are described for selective catalytic reduction diagnosis in an emissions control system or an exhaust system used for treating exhaust gas, such as in a motor vehicle including an internal combustion engine. An example emissions control system includes a selective catalytic reduction (SCR) device. The emissions control system further includes a controller that is performs SCR fault diagnosis. The SCR fault diagnosis includes computing a plurality of estimated NH3 storage capacity values () of an SCR catalyst of the SCR device. The diagnosis further includes determining a diagnostic parameter of the SCR device using the plurality of estimated NH3 storage capacity values.

An apparatus for exhaust gas purification comprises a filter function. The apparatus includes a gas-permeable substrate which forms a wall-flow filter that forms channels. The channels are sealed at least at one end and exhaust gas is flowable through the channels and gas-permeable channel walls of the channels formed from the substrate. A surface of the substrate is provided with an oxygen-storing coating. The mass of an oxygen-storing material coated on the surface of the substrate on an outflow side is higher than the mass of the oxygen-storing material coated on the surface of the substrate on an inflow side.

An exhaust system for an internal combustion engine (28) for controlling the release of undesirable emissions from the engine comprises an exhaust pipe (32) for receiving an exhaust flow from the engine, an SCR catalyst (48) arranged in the exhaust flow and means (80) for determining the temperature of the SCR catalyst. A NOx absorber (38), such as a diesel oxidation and NOx absorber catalyst (DONAC), is located in the exhaust flow at a position upstream of the SCR catalyst (48) for absorbing and releasing NOx contained in the exhaust flow. Means is provided for controlling the NOx absorber (38) so as to control the release of NOx to the SCR catalyst (48) in dependence on the temperature of the SCR catalyst, thereby to effect active management of release of NOx from the DONAC (38).

A catalyst oxygen purge control method may include a catalyst oxygen purge control method during a cold engine period of a catalyst oxygen purge control apparatus which includes a three way catalytic converter through which an exhaust gas combusted when air and fuel are mixed in a combustion chamber is exhausted and the exhaust gas passes, wherein the method includes determining whether a fuel cut condition of an injector which injects the fuel to the combustion chamber is satisfied, performing fuel cut of the injector when the fuel cut condition is satisfied, measuring an oxygen storage capacity of the three way catalyst, and adjusting an oxygen purge time based on the measured oxygen storage capacity.

An exhaust gas control apparatus for an internal combustion engine includes a NO.sub.x storage reduction catalyst, a selective catalytic reduction catalyst, and an electronic control unit configured to shift an operation state of the engine from a rich operation state to a lean operation state, in a case where an acquired temperature of the NO.sub.x storage reduction catalyst is higher than a storage limit temperature, and an acquired NH.sub.3 adsorption amount is equal to or larger than a lower limit adsorption amount when a lean operation restart request is made, and not to shift the operation state from the rich operation state to the lean operation state in a case where the acquired temperature of the NO.sub.x storage reduction catalyst is higher than the storage limit temperature and the acquired NH.sub.3 adsorption amount is smaller than the lower limit adsorption amount when the lean operation restart request is made.

Technical solutions are described for selective catalytic reduction diagnosis in an emissions control system or an exhaust system used for treating exhaust gas, such as in a motor vehicle including an internal combustion engine. An example emissions control system includes a selective catalytic reduction (SCR) device. The emissions control system further includes a controller that is performs SCR fault diagnosis. The SCR fault diagnosis includes computing a plurality of estimated NH3 storage capacity values () of an SCR catalyst of the SCR device. The diagnosis further includes determining a diagnostic parameter of the SCR device using the plurality of estimated NH3 storage capacity values.

An abnormality diagnosis system for an exhaust gas purification device performs abnormality diagnosis of an SCR catalyst on the basis of the concentration of ammonia in exhaust gas in the region downstream of the SCR catalyst. The system includes a controller configured to estimate the amount of ammonia adsorbed in the SCR catalyst in an abnormal condition (ammonia adsorption amount in abnormal condition) and the amount of ammonia adsorbed in the SCR catalyst in a normal condition (ammonia adsorption amount in normal condition). When performing abnormality diagnosis of the SCR catalyst, the controller supplies reducing agent so as to make the ammonia adsorption amount in abnormal condition larger than a first predetermined adsorption amount equal to or larger than a slip start adsorption amount in abnormal condition and to make the ammonia adsorption amount in normal condition smaller than a second predetermined adsorption amount equal to or smaller than a slip start adsorption amount in normal condition.

A method for monitoring and diagnosing an engine exhaust treatment of an internal combustion engine in a motor vehicle includes monitoring a nitrogen oxides (NOx) storage catalyst disposed in an engine exhaust stream downstream of the engine, determining a first diagnostic condition of the NOx storage catalyst based on data from a first EGT sensor and a second EGT sensor; determining a second diagnostic condition of the NOx storage catalyst based on a comparison of temperatures reported by a first NOx sensor and a second NOx sensor, selectively pausing the first diagnostic condition and the second diagnostic condition during a predetermined NOx storage catalyst regeneration period, and selectively generating a notification for an operator of the motor vehicle.