Methods and systems are provided for monitoring a NOx storage capacity of a passive NOx adsorption catalyst (PNA) included in an exhaust gas after-treatment system of an engine. In one example, a method may include, after an engine cold start and prior to an exhaust gas temperature reaching an upper threshold temperature, indicating degradation of the PNA based on an amount of NOx measured downstream of the PNA during a fuel cut event and while the exhaust gas temperature is between a lower threshold temperature and the upper threshold temperature. In this way, degradation of the NOx storage capacity may be inferred based on an amount of NOx released from the PNA and independent of a NOx storage measurement.

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.

Improved systems and methods for dosing agent injection adaptation for a selective catalytic reduction (SCR) system of an engine of a vehicle involve an adaptation procedure that is generally divided into distinct phases based upon the requirement to obtain an accurate dosing adaptation. The phases themselves provide the specific functions of catalyst ammonia storage depletion, catalyst ammonia storage and NOx conversion stabilization, and adaptation value factor determination and verification.

An object of the disclosure is to provide a technology that enables abnormality diagnosis of an NOx trap catalyst to make the diagnosis that the NOx trap catalyst is abnormal even if the degree of deterioration of the NOx trap catalyst is relatively small yet. When performing abnormality diagnosis of an NOx trap catalyst, a system according to the disclosure performs a lean temperature raising process, which is the process of raising the temperature of the NOx trap catalyst to or above a predetermined temperature while keeping the air-fuel ratio of the exhaust gas flowing into the NOx trap catalyst at a lean air-fuel ratio. The system diagnoses abnormality of the NOx trap catalyst on the basis of the NOx storage efficiency of the NOx trap catalyst or a parameter correlating with that NOx storage efficiency after the completion of the lean temperature raise process.

The present disclosure describes methods for evaluating quality of DEF dosed to an EAS including a close coupled SCR unit a downstream SCR unit. A NOx conversion efficiency of the close coupled SCR unit and a NOx conversion efficiency of the downstream SCR unit are used to evaluate quality of DEF. In some embodiments, the NOx conversion efficiency of close coupled SCR unit is used to evaluate quality of DEF. Operation of an EAS using the results of the evaluation of quality of DEF are described.

Systems and methods for diagnosing at least one component in an exhaust aftertreatment system are provided. The system includes an exhaust aftertreatment system coupled to an engine system, at least one sensor, and at least one processing circuit structured to: receive initial sensor data; determine an initial parameter value based on the initial sensor data; determine that the initial parameter does not satisfy an initial threshold; perform operations to diagnose at least one component of the exhaust aftertreatment system comprising: causing the engine system to operate through a sequence of a plurality of engine outputs; receiving a plurality of sensor data, each of the plurality sensor data corresponding to at least one of the plurality of engine outputs; comparing each of the plurality of sensor data to a corresponding threshold; and diagnosing the at least one component based on the comparison.

A system includes a catalyst for receiving and treating exhaust gas generated by an engine, a passive NOx adsorber (PNA) positioned upstream of the catalyst, a bypass valve positioned upstream of the catalyst and the PNA, and a controller. The controller is configured to, determine that the catalyst is operating under cold start conditions, control the bypass valve to direct exhaust gas to the PNA, determine that the catalyst is no longer operating under cold start conditions and continue to control the bypass valve to direct exhaust gas to the PNA for a predetermined duration, and after the elapse of the predetermined duration, control the bypass valve to direct exhaust gas to the catalyst bypassing the PNA. The controller is also configured to detect a high transient torque demand while the exhaust gas is provided to the PNA, and split the torque demand between the engine and an electric motor.

An exhaust purification system is provided with a NOx-occlusion-reduction-type catalyst 32 that occludes NOx in exhaust when the exhaust is in a lean state and reduces and purifies the occluded NOx when the exhaust is in a rich state, and a NOx purge rich control unit 140 for reducing and purifying NOx occluded in the NOx-occlusion-reduction-type catalyst 32 by putting the exhaust into the rich state by repetitively performing fuel injection control of at least one of post injection and exhaust pipe injection at a predetermined interval.

A system for determining a performance status of an exhaust aftertreatment system may include determining an ammonia-to-nitrogen ratio using a sample ammonia input value and a sample NO.sub.x input value. An actual NO.sub.x input value and an actual ammonia input value can be received. An emission value from may be received from a first sensor. A NO.sub.x emission estimate, an ammonia slip estimate, and an optimal ammonia storage value for a selective catalytic reduction may be determined using an iterative inefficiency calculation based, at least in part, on the actual NO.sub.x input value, the actual ammonia input value, and the ammonia-to-nitrogen ratio; and the NO.sub.x emission estimate, the ammonia slip estimate, and the optimal ammonia storage value may be outputted to a diagnostic system.

There is provided a technology pertaining to abnormality diagnosis of an NSR catalyst that enables the diagnosis that the NSR catalyst is abnormal to be made even when the degree of deterioration of the NSR catalyst is relatively small yet. An abnormality diagnosis apparatus is applied to an exhaust gas purification apparatus having an NSR catalyst and a fuel addition valve. The abnormality diagnosis apparatus includes a controller configured to perform a specific fuel addition process and diagnose the NSR catalyst. The controller starts the specific fuel addition process when the NSR catalyst is in a specific start condition, and diagnoses the NSR catalyst on the basis of the quantity of NOx flowing out of the NSR catalyst over a specific period in the period from when the specific fuel addition process is started to when the temperature of the NSR catalyst reaches the thermal desorption temperature.