A diesel exhaust fluid (DEF) control system includes: a target module configured to determine a target rate of injection of a DEF by a DEF injector; an adjustment module configured to determine an adjustment based on a concentration of urea in the DEF; an adjusting module configured to adjust the target rate based on the adjustment to produce an adjusted rate of injection of the DEF by the DEF injector; and an injector control module configured to control injection of the DEF by the DEF injector based on the adjusted rate.

A diesel exhaust fluid (DEF) control system includes: a target module configured to determine a target rate of injection of a DEF by a DEF injector; an adjustment module configured to determine an adjustment based on a concentration of urea in the DEF; an adjusting module configured to adjust the target rate based on the adjustment to produce an adjusted rate of injection of the DEF by the DEF injector; and an injector control module configured to control injection of the DEF by the DEF injector based on the adjusted rate.

A thermal overload of an internal combustion engine and of cooling system of a combustion machine due to a raising of the temperature of the exhaust gas flowing through an exhaust gas line of the combustion machine, which is provided as a measure to desulfurize a NO.sub.x storage catalytic converter and/or to regenerate a particulate filter, is prevented in that before and/or during this measure, the cooling output for the coolant flowing through the cooling system is systematically increased in order to achieve a lowering of the coolant temperature to a value range that lies below what would normallythat is to say, without the simultaneous desulfurization of the NO.sub.x storage catalytic converter and/or without the regeneration of the particulate filterhave been provided for the operation of the combustion machine in a corresponding operating state of the internal combustion engine.

A method for monitoring a gas sensor (14) which comprises two electrochemical measuring cells (20, 30) and which is arranged in an exhaust tract (10) of an internal combustion engine (11), wherein the sensor elements (20, 30) exhibit a substantially identical sensitivity towards a first gas component and a different sensitivity towards a second gas component and are insensitive towards further gas components. In an operating state in which an exhaust gas stream at the gas sensor (14) contains less of the second gas component than of the first gas component a concentration of the first gas component is calculated from each of the sensor signals from the sensor elements (20, 30) and a defect in a sensor element (20, 30) is deduced from the concentrations of the first gas component.

A method and a control device for regulating a modeled fill level of an exhaust gas component reservoir of a catalytic converter of an internal combustion engine. Regulation of the modeled fill level is accomplished using a system model. An actual maximum storage capacity of the catalytic converter for the exhaust gas component is ascertained during operation of the internal combustion engine and is taken into consideration in regulating the modeled fill level.

Rich spike is carried out in an efficient manner. In an exhaust gas purification apparatus for an internal combustion engine which performs lean burn operation, the apparatus includes an NOx storage reduction catalyst, a controller to carry out rich spike, to calculate a storage amount of NOx, to calculate a storage amount of nitrates, and calculate a nitrate ratio, wherein the controller controls a timing at which the rich spike is carried out, based on the nitrate ratio.

An engine control device is provided, which includes an oxidation catalyst provided in an exhaust passage to oxidize unburned fuel within exhaust gas, a NO.sub.x catalyst provided integrally with or downstream of the oxidation catalyst, a PM filter provided in the exhaust passage downstream of the oxidation catalyst to capture fine particulate matter within the exhaust gas, a fuel injector, and a controller. When the particulate matter is accumulated by a given amount, the controller starts a PM filter regeneration control to remove the particulate matter, and after this control is started and when the accumulation amount decreases by a given amount, the controller starts a NO.sub.x catalyst regeneration control to switch between a first state in which an air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or less and a second state in which the air-fuel ratio is higher than the stoichiometric air-fuel ratio.

An exhaust gas control apparatus for an internal combustion engine includes a NO.sub.X storage reduction catalyst, a selective catalytic reduction catalyst, and an electronic control unit configured to shift an operation state of the engine from a rich operation state to a lean operation state, in a case where an acquired temperature of the NO.sub.X storage reduction catalyst is higher than a storage limit temperature, and an acquired NH.sub.3 adsorption amount is equal to or larger than a lower limit adsorption amount when a lean operation restart request is made, and not to shift the operation state from the rich operation state to the lean operation state in a case where the acquired temperature of the NO.sub.X storage reduction catalyst is higher than the storage limit temperature and the acquired NH.sub.3 adsorption amount is smaller than the lower limit adsorption amount when the lean operation restart request is made.

Methods and systems are featured for reducing harmful exhaust gas components of combustion devices such as gasoline-powered combustion engines (e.g., predominately stoichiometric running engines). The methods and systems include an underbody combination of a hydrocarbon trap (HCT), suited for cold start hydrocarbon adsorption, as well as an associated NOx trap. The system is inclusive of a control unit for extending a lean exhaust condition reaching the desorbing HCT as to avoid a deficiency in oxygen during the time period of HCT desorption. The system is also inclusive of one or more TWCs as in one associated with the underbody HCT-NOx-trap combination and/or one positioned in a close coupled position. Platinum group metals as in Pd, Rh and Pt are also featured on one, two or all three of the HCT, NOx-trap, and TWC when present.

Methods and systems are provided for a low temperature NOx adsorber (LTNA). In one example, a method includes operating in a first mode, the first mode including storing exhaust NOx in an LTNA, heating the LTNA until an LTNA outlet temperature reaches a first threshold temperature, and then converting released NOx in a downstream selective catalyst reduction (SCR) device; and operating in a second mode, the second mode including heating the LTNA until the LTNA outlet temperature reaches a second threshold temperature, higher than the first threshold temperature, and converting exhaust NOx in the SCR device.