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.

A method for the diagnosis of an air supply circuit supplying air to a burner of an exhaust gas after-treatment system for an exhaust system of an internal combustion engine, wherein the air supply circuit is provided with a pumping device housed along a first duct adjusted by a shut-off valve. The method entails housing a first pressure sensor along the first duct interposed between the pumping device and the burner; housing a second pressure sensor along a second duct out of the burner; acquiring the pressure signals detected by said first and second pressure sensors; and diagnosing faults and/or malfunctions in the air supply circuit depending on the pressure signals detected by said first and second pressure sensors.

The disclosure relates to a method and a device for diagnosing coking of a secondary air system of an internal combustion engine. The secondary air system has an intake air line for providing secondary air, a secondary air pump for compressing the secondary air, a secondary air valve for controlling the secondary air injection, a pressure sensor that is arranged in the secondary air system downstream of the secondary air pump and upstream of the secondary air valve, and an injection line for injecting the secondary air into an exhaust tract of the internal combustion engine.

A method for operating a petrol engine, in which air is introduced into an exhaust tract through which exhaust gas from the petrol engine can flow, bypassing the petrol engine, includes introducing the air into the exhaust tract at a point arranged downstream of a first three-way catalytic converter arranged in the exhaust tract and upstream of a second three-way catalytic converter arranged in the exhaust tract downstream of the first three-way catalytic converter, while the petrol engine is operated with a sub-stoichiometric combustion air ratio, where a desulphurization of the second three-way catalytic converter is effected.

Methods and systems are provided for mitigating hydrocarbon breakthrough from an onboard fuel vapor canister during an engine-off condition. In one example, a method may include actively routing ambient air to an exhaust catalyst to reducing a temperature of the exhaust catalyst.

The invention relates to an exhaust gas aftertreatment system for an internal combustion engine (10), in particular for an internal combustion engine (10) which is charged by means of a turbocharger (30) and spark-ignited by means of spark plugs (16). A particulate filter (24) and an electrically heatable three-way catalytic converter (26) downstream of the particulate filter (24) are arranged in a position close to the engine in an exhaust gas system (20) connected to an outlet (12) of the internal combustion engine (10). A further three-way catalytic converter (28) is arranged in the underbody position of the motor vehicle downstream of the electrically heatable catalytic converter (26). According to the invention, the electrically heatable three-way catalytic converter (26) is heated electrically after engine start, and the particulate filter (24), the electrically heatable three-way catalytic converter (26) and the further three-way catalytic converter are additionally heated by the exhaust gas flow from the internal combustion engine (10). The electric heating of the electrically heatable three-way catalytic converter (26) is switched off when the electrically heatable three-way catalytic converter (26) has reached its light-off temperature.

The invention relates to a regeneration air system for an exhaust aftertreatment system of an internal combustion engine and to such an exhaust aftertreatment system. The regeneration air system comprises a regeneration air delivery element, a regeneration air duct, and a regeneration air valve. A sensor system is provided in the regeneration air duct with which a regeneration air mass flow {dot over (m)}.sub.SL can be determined exactly. The exhaust aftertreatment system comprises an exhaust system with an exhaust duct in which, in the direction of flow of an exhaust gas through the exhaust duct, a three-way catalytic converter is arranged underhood and a four-way catalytic converter is arranged downstream. A provision is made that an intake point for the regeneration air from the regeneration air system is formed on the exhaust duct downstream from the underhood three-way catalytic converter and upstream from the four-way catalytic converter.

An internal combustion engine comprises a filter and is configured to enable attachment of a secondary air feed system feeding air into exhaust gas flowing into the filter. A control device of the engine is configured, in the PM removal control for removing particulate matter deposited on the filter, to perform temperature raising processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body 1 is a rich air-fuel ratio and for feeding air from the secondary air feed system, and to perform regeneration processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body is a stoichiometric air-fuel ratio and for feeding air from the secondary air feed system so that the air-fuel ratio of the exhaust gas flowing into the filter is a lean air-fuel ratio.

A method for operating an internal combustion engine which has an exhaust-gas system in which a first exhaust-gas purification component and a second exhaust-gas purification component are arranged, and which has an opening-in point via which secondary air can be injected into the exhaust-gas system. The method is distinguished by the fact that an outlet concentration of the at least one exhaust-gas constituent prevailing at an outlet of the first exhaust-gas purification component is calculated by means of an outlet emissions model, and that an inlet concentration of the at least one exhaust-gas constituent prevailing at an inlet of the second exhaust-gas purification component is determined in a manner dependent on the calculated outlet concentration, and that the internal combustion engine is operated in a manner dependent on the thus determined inlet concentration of the at least one exhaust-gas constituent.

A catalyst warming apparatus includes an air blower, a fuel feeder, and an air blowing controller. The air blower is disposed between an engine and a purification catalyst in an exhaust pipe communicating with the engine and is configured to blow air toward the purification catalyst. The fuel feeder is configured to cause the purification catalyst to retain fuel. The air blowing controller is configured to start driving the air blower at a predetermined start timing before a start of the engine.