A method and an apparatus including a processing circuit structured to: receive a first signal indicative of an upstream air-fuel equivalence ratio from a first sensor positioned upstream of an intake of a catalyst, the first signal defining a duty cycle, receive a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst, adjust the duty cycle based at least in part on the second signal, and provide a fault signal in response to the duty cycle not meeting a duty cycle range for a predetermined period of time. A notification circuit is structured to provide a notification indicating that the second sensor is faulty in response to receiving the fault signal.

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.

In a control device for an internal combustion engine, a learning map includes at least one partitioned operating region. The at least one partitioned operating region corresponds to at least one of operating conditions of the internal combustion engine. The learning map includes a value of at least one control parameter stored in the at least one partitioned operating region. A control unit controls the internal combustion engine in accordance with the at least one control parameter. An updating unit learns a value of the at least one control parameter for the at least one of the operating conditions, thus performing an updating of the value of the at least one control parameter stored in the at least one partitioned operating region to the learned value. A partition changing unit changes a partition pattern of the learning map.

A vehicle control apparatus for a vehicle includes a catalyst deterioration diagnosing unit, an engine controlling unit, and a diagnosis start determining unit. The catalyst deterioration diagnosing unit executes a deterioration diagnosis of a catalyst included in an exhaust system of an engine provided in the vehicle. The engine controlling unit controls an air-fuel ratio of the engine to a lean side and thereafter to a rich side during the deterioration diagnosis of the catalyst. The diagnosis start determining unit prohibits the deterioration diagnosis of the catalyst from being executed when a deceleration rate upon deceleration of the vehicle is high, and permits the deterioration diagnosis of the catalyst to be executed when the deceleration rate upon deceleration of the vehicle is low.

A method (200) for determining an amount of hydrocarbons in an exhaust gas (10) downstream of a lean-operation internal-combustion engine (110), comprising the following steps: observing a first catalyst heating mode of the internal-combustion engine (110) at a high catalyst temperature, wherein a predefinable amount of fuel having a predominantly non-combusting portion is introduced into a combustion chamber of the internal-combustion engine (110); determining an actual temperature change downstream of an oxidation catalyst (120) downstream of the internal-combustion engine (110) during the first catalyst heating mode; and determining the amount of hydrocarbons (cHC) in the exhaust gas (10) upstream of the oxidation catalyst (120) based on the actual temperature change. Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

The invention relates to an internal combustion engine with an air intake system and an exhaust system is embodied as an internal combustion engine, in particular a gasoline engine, that is charged by means of an exhaust gas turbocharger. At least one three-way catalytic converter is arranged in the exhaust system of the internal combustion engine. Furthermore, a low-pressure exhaust gas recirculation system is provided that connects the exhaust system downstream from a turbine of the exhaust gas turbocharger and upstream from the at least one three-way catalytic converter to the air intake system upstream from a compressor of the exhaust gas turbocharger. The invention further relates to a method for exhaust aftertreatment of such an internal combustion engine.

A method for operating an internal-combustion engine having an exhaust gas catalyst, a first exhaust gas sensor upstream of the exhaust gas catalyst and a second exhaust gas sensor downstream of the exhaust gas catalyst. A fill level of an exhaust gas component that can be stored in the exhaust gas catalyst is determined using a theoretical catalyst model, into which, as the input value, a signal of the first exhaust gas sensor (a first signal); a signal of the second exhaust gas sensor (a second signal); and a target signal are provided. The target signal corresponds to the signal that would be expected at the determined fill level in the exhaust gas catalyst. The catalyst model is reinitiated when the deviation of the second signal from the target signal exceeds a predetermined threshold value. The fill level is also regulated, and an air-fuel mixture is adjusted.

Methods and systems are provided for an exhaust system. In one example, a method may include determining presence of a zone flow based on a comparison of a first exhaust sensor and a second exhaust sensor. The presence or absence of the zone flow may determine a rate at which an air-fuel ratio is adjusted.

The abnormality diagnosis system 1 of a downstream side air-fuel ratio detection device 41, 42, comprises an air-fuel ratio control part 71 controlling an air-fuel ratio of an air-fuel mixture, an abnormality judgment part 72 judging abnormality of the downstream side air-fuel ratio detection device based on a characteristic of change of output of the downstream side air-fuel ratio detection device when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change, and an oxygen change calculation part 73 calculating an amount of change of an oxygen storage amount of the catalyst when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change. The abnormality judgment part does not judge abnormality of the downstream side air-fuel ratio detection device when the amount of change of the oxygen storage amount is less than a lower limit threshold value.

In an opposed-piston engine which includes a catalytic aftertreatment device in its exhaust system an exhaust gas condition indicating a catalyst temperature of the aftertreatment device is monitored. When the catalyst temperature is near or below a light-off temperature, a catalyst light-off procedure is executed to elevate the temperature of the catalyst.