Methods and systems are provided for operating an engine of a vehicle. In one example, a method may include positioning an oxygen sensor in an engine exhaust downstream from a selective catalytic reduction (SCR) catalyst, determining an oxygen storage capacity of the SCR catalyst based on a measurement of the oxygen sensor, and determining an extent of deactivation of the SCR catalyst based on the oxygen storage capacity.

An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine comprises an aftertreatment component and an optical assembly. The optical assembly comprises an optical emitter configured to emit light onto a face of the aftertreatment component, and an optical detector configured to detect light reflected from the face of the aftertreatment component. A controller is configured to determine at least one of an amount of NOx gases or an amount of ammonia on the face of the aftertreatment component based on an optical parameter of the detected light that has reflected from the face of the aftertreatment component.

A method and system for mitigating a urea deposit within an SCR system that includes determining a mass of an accumulated urea deposit present within the SCR catalyst and SCR piping, comparing the mass of the accumulated urea deposit with a deposit upper threshold limit, and initiating an SCR regeneration event when the mass of the accumulated urea deposit is greater than the deposit upper threshold limit. The method further includes determining an amount of NH.sub.3 passing through the SCR catalyst downstream of the urea deposit, comparing the amount of NH.sub.3 passing through the SCR catalyst with an NH.sub.3 regeneration threshold limit, and terminating the SCR regeneration event when the level of NH.sub.3 passing through the SCR catalyst is less than the SCR NH.sub.3 regeneration threshold.

A gas sensor, and a method for measuring the concentrations of a plurality of target components in a gas to be measured are disclosed. The gas sensor is provided with: a specific component measurement means which measures the concentration of a specific component in a measurement chamber; a preliminary oxygen concentration control means which controls the oxygen concentration in a preliminary adjustment chamber; a drive control means which controls the driving and stopping of the preliminary oxygen concentration control means; and a target component acquisition means which, on the basis of the difference between sensor outputs from the specific component measurement means when the preliminary oxygen concentration control means is being driven and when the preliminary oxygen concentration control means is stopped, and one of the respective sensor outputs, acquires the concentrations of a first target component and a second target component.

An exhaust aftertreatment system includes a particulate filter element and a particulate matter sensor that is disposed to monitor the exhaust gas feedstream downstream of the particulate filter element. A method for monitoring the exhaust gas feedstream includes determining a temperature associated with the particulate matter sensor and monitoring engine operation and the exhaust aftertreatment system. A magnitude of ammonia is determined in the exhaust gas feedstream proximal to the particulate matter sensor based upon the monitoring of the engine operation and the exhaust aftertreatment system. An initial reading is determined from the particulate matter sensor and is adjusted based upon the magnitude of ammonia in the exhaust gas feedstream proximal to the particulate matter sensor and the temperature of the particulate matter sensor. A magnitude of particulate matter in the exhaust gas feedstream is determined based upon the adjusted initial reading from the particulate matter sensor.

A selective catalytic reduction system control system (10) and method of its use include an ammonia (“NH.sub.3”) slip sensor (13) located within an interior space (27) of an exhaust stack (15) of a selective catalytic reactor (31), toward an inlet end (25) of the stack (15); a housing (17) located within the interior space of the exhaust stack; the housing including face panels 19; a nitrogen oxides (“NOx”) sensor (11) contained within an interior space (29) defined by the face panels of the housing, at least two of the face panels (19.sub.I, 19.sub.O) containing an oxidation catalyst; and a dosing controller (59) in communication with the NH.sub.3 and NOx sensors, the dosing controller including a microprocessor with dosing logic embedded thereon. The housing with oxidation catalyst acts as a linear box, isolating the NOx sensor from NH.sub.3 slip, linearizing the NOx sensor signal.

A selective catalytic reduction system control system (10) and method of its use include an ammonia (“NH.sub.3”) slip sensor (13) located within an interior space (27) of an exhaust stack (15) of a selective catalytic reactor (31), toward an inlet end (25) of the stack (15); a housing (17) located within the interior space of the exhaust stack; the housing including face panels 19; a nitrogen oxides (“NOx”) sensor (11) contained within an interior space (29) defined by the face panels of the housing, at least two of the face panels (19.sub.I, 19.sub.O) containing an oxidation catalyst; and a dosing controller (59) in communication with the NH.sub.3 and NOx sensors, the dosing controller including a microprocessor with dosing logic embedded thereon. The housing with oxidation catalyst acts as a linear box, isolating the NOx sensor from NH.sub.3 slip, linearizing the NOx sensor signal.

In a process for adapting an amount of reducing agent for a removal of nitrogen oxides from the gases in an exhaust line, a first alignment of the amounts of nitrogen oxides measured by upstream and downstream sensors is performed without injection of agent and with a catalyst of the system emptied of ammonia. A second alignment of the estimated reduction of nitrogen oxides with the measured reduction is performed by a difference between amounts of nitrogen oxides upstream and downstream during a substoichiometric injection of reducing agent without creating a store of ammonia in a catalyst of the system with a first correction of the amount of agent. A third alignment of an estimated efficiency of retaining nitrogen oxides with a efficiency measured by the sensors is performed, this third alignment taking place via a second correction of the amount of reducing agent injected as an adaptive correction.

Methods comprising: arranging a binary lambda sensor and a second sensor downstream of a catalytic converter; when the engine is run for the first time, using an initial lambda setpoint for closed-loop control; measuring the NH.sub.3 value in the exhaust gas; simultaneously measuring the signal from the binary lambda sensor; if the NH.sub.3 value lies above a first threshold value, reducing the lambda setpoint value of the binary lambda signal until the NH.sub.3 value lies below the first threshold value or the binary sensor signal lies below a second threshold value; recording the corresponding binary sensor signal when the NH.sub.3 value passes the first threshold value, for binary sensor signal setpoint value adaptation, as V.sub.binary-left; and calculating the real lambda setpoint value.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.