Methods and systems are provided for adjusting an ammonia (NH.sub.3) sensor output using readings of a nitrogen oxide (NOx) sensor, the NOx sensor having a sensitivity factor to NH.sub.3. In one example, a method may include determining and updating a gain value of the NH.sub.3 sensor during zero NOx conditions to be used to calculate a corrected NH.sub.3 sensor output value, and determining and updating an offset value of the NH.sub.3 sensor during zero NH.sub.3 conditions to be used to zero the NH.sub.3 sensor during zero NOx conditions.

Systems, apparatuses, and methods for monitoring a catalyst health parameter are provided. A system includes one or more processing circuits having one or more memory devices coupled to one or more processors. The one or more memory devices store instructions that, when executed by the one or more processors, cause the one or more processors to: receive information indicative of at least one of a temperature of exhaust gas entering the aftertreatment system, a time at idle, or a mass flow of exhaust gas; determine a catalyst health management criteria based on the information; determine a catalyst health indicator based on the catalyst health management criteria being met; compare the determined catalyst health indicator to a predetermined health threshold criteria; and provide a notification based on the determined catalyst health indicator being less than the predetermined health threshold criteria.

A management device 100 includes: a data acquisition unit 122 configured to acquire cumulative data for each parameter related to stress acting on a DOC 33 configured to purify exhaust gas of an engine and an exhaust gas temperature of the exhaust gas raised for purification; a damage degree identification unit 123 configured to identify a degree of damage to the DOC 33 based on the acquired cumulative data; a relationship identification unit 124 configured to identify a relational expression indicating a relationship between the identified degree of damage and the exhaust gas temperature; an target information acquisition unit 125 configured to acquire an exhaust gas temperature of exhaust gas raised for purification performed by the DOC 33; and a diagnosis unit 126 configured to estimate a degree of damage to the DOC 33 based on the acquired exhaust gas temperature and the identified relational expression.

A computer-implemented method for determining whether a reductant (e.g. urea) injector is clogged is provided. The method includes receiving data indicative of an injector duty cycle and a pump duty cycle. Using a trained machine learning module, at least a first value is calculated, indicative of a probability of the injector being clogged. The method further includes providing, based on the first value, an indication of whether the reductant injector is clogged. A device for providing the indication using the method, a computer program, a reductant injector system, and e.g. a combustion engine including such a reductant injector system are also provided.

A control module for an aftertreatment system that includes a selective catalytic reduction (SCR) catalyst and an oxidation catalyst, comprises a controller configured to be operatively coupled to the aftertreatment system. The controller is configured to determine an actual SCR catalytic conversion efficiency of the SCR catalyst. The controller determines an estimated SCR catalytic conversion efficiency based on a test sulfur concentration selected by the controller. In response to the estimated SCR catalytic conversion efficiency being within a predefined range, the controller sets the test sulfur concentration as a determined sulfur concentration in a fuel provided to the engine. The controller generates a sulfur concentration signal indicating the determined sulfur.

Various embodiments of the teachings herein include methods for determining the sulfur content in an exhaust tract of a motor vehicle. The method may include: determining a change in the nitrogen oxide abatement efficiency of a coated particulate filter arranged in the exhaust tract and/or a determined ammonia storage capacity change of a coated particulate filter arranged in the exhaust tract; comparing the determined change to a threshold value; identifying an excessive sulfur content if the comparison shows that the determined change exceeds the threshold value; and undertaking one or more corrective actions in response to identifying an excessive sulfur content.

Various embodiments include a method for regenerating a coated particulate filter arranged in an exhaust-gas duct of a motor vehicle. The method may include: detecting a need for particulate filter regeneration; determining a first diagnosis value before initiating particulate filter regeneration; after determining the first diagnosis value, carrying out particulate filter regeneration; determining a second diagnosis value after particulate filter regeneration; determining a difference between the first determined diagnosis value and the second determined diagnosis value; comparing the determined difference with a threshold value; and identifying a particulate filter defect if the determined difference exceeds the threshold value.

In a method and a device for monitoring the operability of an emission control system of an internal combustion engine, at least two catalytic converters are situated in succession in an exhaust duct. For tracking control, breakthrough detection for diagnosing the first catalytic converter, and for a second balancing for the storage capacity of oxygen or rich gas of the second catalytic converter, a two-point lambda probe be used and, for the latter, tolerance and aging effects are compensated. This results in particular in cost advantages in emission control systems for fulfilling stricter emission and diagnostic requirements.

An EHC line leakage diagnosis method can operate a heater of an oxygen detector when satisfying one or more conditions of an engine off time, a coolant temperature, and an outside air temperature by a diagnosis controller upon the key-on of the non-operation of an engine, and then, determine the normality or abnormality of a temperature drop using a change in a temperature value of a signal value and the temperature value detected by the oxygen detector after an air pump is driven, and then confirm the leakage of an exhaust line and a line on the rear end portion of an EHC valve of an air line using the number of times of the occurrence of the abnormality of the temperature drop, and can perform the failure diagnosis without generating the exhaust gas by not operating an engine.

An apparatus includes a dosing module structured to suspend dosing in an exhaust aftertreatment system; a selective catalytic reduction (SCR) inlet NOx module structured to interpret SCR inlet NOx data and an SCR inlet temperature; a SCR outlet NOx module structured to interpret SCR outlet NOx data; and a system diagnostic module structured to determine an efficiency of a SCR system based on the SCR inlet and outlet NOx data over a range of SCR temperatures, wherein the system diagnostic module is further structured to determine a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR temperature range and the SCR efficiency at a relatively lower SCR temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold.