Methods and systems are provided for a dual function imaging device. In one example, a method may comprise imaging exhaust gas outside of a reverse engine condition via the imaging device. The imaging device may image a surrounding area during the reverse engine condition.

A method for determining the hydrocarbon (HC) oxidation performance of an oxidation catalyst device (OC) includes communicating gas to the OC inlet over a time frame, measuring the NOx content of the OC outlet gas using a NOx sensor over the time frame, wherein the temperature of the OC increases over the time frame, and correlating an increased NOx measurement over the time frame to an increased OC HC oxidation performance. The NOx sensor can be operated in a low temperature mode during the time frame. The method can further include determining the temperature of the OC over the time frame and correlating the HC oxidation performance to the OC temperature, and/or correlating a maximum NOx concentration measured during the time frame to the OC temperature measured at the same time. HC slip through the OC can be identified when the measured NOx content of the OC outlet gas decreases.

An exhaust emission control system of an engine is provided including a NO.sub.x catalyst for oxidizing HC and storing NO.sub.x within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the NO.sub.x when the air-fuel ratio is approximately stoichiometric or rich. The system includes a SCR catalyst for purifying NO.sub.x by causing a reaction with NH.sub.3, a urea injector, a fuel injection controlling module, and a processor configured to execute a NO.sub.x reduction controlling module for performing a NO.sub.x reduction control to enrich the air-fuel ratio to reach a target ratio. When the urea injection is determined to be abnormal, the NO.sub.x reduction controlling module performs a NH.sub.3-supplied NO.sub.x reduction control in a state where a larger amount of unburned fuel than the amount of unburned fuel in the exhaust passage in the NO.sub.x reduction control is supplied to the exhaust passage.

A method for detecting the aging of a heterogeneous catalytic converter, including the following steps: acquiring at least one measurement signal in a media flow passing through the catalytic converter downstream of the catalytic converter; applying a time-variant input signal to the media flow and/or the catalytic converter; evaluating a behavior of the at least one measurement signal as a function of the time-variant input signal; and detecting a state of aging of the catalytic converter.

A method for determining the hydrocarbon (HC) oxidation performance of an oxidation catalyst device (OC) includes communicating gas to the OC inlet over a time frame, measuring the NOx content of the OC outlet gas using a NOx sensor over the time frame, wherein the temperature of the OC increases over the time frame, and correlating an increased NOx measurement over the time frame to an increased OC HC oxidation performance. The NOx sensor can be operated in a low temperature mode during the time frame. The method can further comprise determining the temperature of the OC over the time frame and correlating the HC oxidation performance to the OC temperature, and/or correlating a maximum NOx concentration measured during the time frame to the OC temperature measured at the same time. HC slip through the OC can be identified when the measured NOx content of the OC outlet gas decreases.

A method for diagnosing the degree of deterioration of a catalyst disposed in an exhaust path of an internal combustion engine and oxidizes or adsorbs a target gas, including at least one of a hydrocarbon gas and a carbon monoxide gas in an exhaust gas from the internal combustion engine, is adapted to determine whether deterioration exceeding an acceptable level of a catalyst occurs or not by comparing the concentration of a target gas detected downstream from the catalyst in the exhaust path when a diagnosis-gas atmosphere containing a target gas higher in concentration than a target gas during a steady-operation state of the internal combustion engine is intentionally produced and introduced into the catalyst with a threshold value corresponding to the temperature of a catalyst at the timing which the diagnosis-gas atmosphere is introduced.

Provided is a method for accurately diagnosing a degree of degradation of an oxidation catalyst. A target gas detecting element configured to output an electromotive force corresponding to a concentration of a target gas is provided downstream of a catalyst in an exhaust path of an internal combustion engine. A sum of change amounts of an electromotive force in a time-variable profile thereof after the introduction of a gas atmosphere for diagnosis into the catalyst is set as a diagnosis index value. The gas atmosphere has been intentionally created in the engine and includes a target gas having a concentration higher than the concentration of a target gas during a steady operation state of the engine. The index value is then compared with a threshold corresponding to the temperature of the catalyst to diagnosis whether degradation exceeding an acceptable degree has occurred in the catalyst.

Provided is a method for accurately diagnosing a degree of degradation of an oxidation catalyst. A target gas detecting element configured to output an electromotive force corresponding to a concentration of a target gas is provided downstream of a catalyst in an exhaust path of an internal combustion engine. A maximum change amount of an electromotive force after the introduction of a gas atmosphere for diagnosis into the catalyst is set as a diagnosis index value. The gas atmosphere has been intentionally created in the engine and includes a target gas having a concentration higher than the concentration of a target gas in a steady operation state of the engine. The index value is then compared with a threshold corresponding to the temperature of the catalyst to diagnosis whether degradation exceeding an acceptable degree has occurred in the catalyst.

A system and method are disclosed for desulfating an oxidation catalyst in an aftertreatment system of a multifuel internal combustion engine. The oxidation catalyst can be desulfated in response to one or more desulfation triggering events. The desulfation process includes providing hydrocarbons from one or all of the multiple fuel sources to an upstream oxidation catalyst. The hydrocarbons react with the exhaust gas within the upstream oxidation catalyst to deplete oxygen in the exhaust flow to thereby reduce the desulfation temperature of the oxidation catalyst while elevating a temperature of the exhaust gas to a desulfation temperature range.

A method for operating an aftertreatment system of an engine is disclosed. The method includes measuring, using one or more sensors, at least one operating parameter of the engine system; estimating, by a controller, a mass of hydrocarbon retained by an aftertreatment component using the at least one operating parameter; determining, by the controller, a percent load of hydrocarbon using the mass of hydrocarbon; comparing, by the controller, the percent load to a predetermined hydrocarbon load threshold; and providing at least one alert indicating a need to initiate a stepwise increase in an engine power to one or more predetermined engine speeds for one or more predetermined durations, if the percent load exceeds the predetermined hydrocarbon load threshold.