A heavy-duty truck has a diesel engine, an exhaust after-treatment system, and an engine control unit. The exhaust after-treatment system includes a close-coupled selective catalytic reduction system and an underbody selective catalytic reduction system, a first NO.sub.x sensor upstream of the close-coupled selective catalytic reduction system, a second NO.sub.x sensor between the two selective catalytic reduction systems, and a third NO.sub.x sensor downstream of the underbody selective catalytic reduction system. The engine control unit may perform methods allowing intrusive diagnostics to be performed on exhaust gas NO.sub.x sensors using the selective catalytic reduction systems during normal operation of the heavy-duty truck.

A controller controls energization of a filter and a fuel addition valve in an exhaust purifying apparatus. The controller executes a filter regeneration process when an electrical resistance value between two electrodes fixed to an outer surface of the filter is less than a predetermined regeneration determination value. The controller executes a soot burning process when the electrical resistance value is greater than or equal to the regeneration determination value and less than a soot burning determination value, which is set in advance to be larger than the regeneration determination value.

An automated diesel exhaust fluid (DEF) system and method for refilling DEF. The automated DEF system provides DEF refilling after an initial setup and without manual intervention. The automated DEF system includes a electric DEF flow control device that controls the flow of DEF. The electric DEF flow control device may include control circuitry, an electrics enclosure that encloses the control circuity, an electric fluid sensor, a valve, a beacon light, a status light, a button, a threaded swivel connection, and a mandrel on the inside of the threaded swivel connection.

A plasma generator includes an AC power supply, a power supply electrode and a ground electrode, one of which is disposed in a gas flow path and the other of which is a conductive wall constituting the gas flow path, an inflexible connection member configured to electrically connect the AC power supply and the power supply electrode, and an insulating material (power supply side insulating material, ground side insulating material) covering a side of one of the power supply electrode and the ground electrode, the side facing the other electrode.

A controller controls energization of a filter and a fuel addition valve in an exhaust purifying apparatus. The controller executes a filter regeneration process when an electrical resistance value between two electrodes fixed to an outer surface of the filter is less than a predetermined regeneration determination value. The controller executes a soot burning process when the electrical resistance value is greater than or equal to the regeneration determination value and less than a soot burning determination value, which is set in advance to be larger than the regeneration determination value.

In a control apparatus, a heater adjuster performs a regeneration task of causing a heater to heat a sensing member of a particulate matter sensor to burn particulate matter deposited on the sensing member to thereby remove the particulate matter from the sensing member. The heater adjuster performs a deposition reduction task of maintaining, for a predetermined duration, a temperature of the sensing member at a deposition reduction temperature that reduces additional particulate-matter deposition on the sensing member. The predetermined duration is defined from completion of a regeneration task to a time when an environmental condition around the particulate matter sensor is determined to be stable. The heater adjuster stops the heater from heating the sensing member if a condition determiner determines that the environmental condition around the particulate matter sensor is stable.

Systems and methods for providing electric energy to an electrically heated catalyst are described. In one example, the electrically heated catalyst may be a three phase device with heating elements that are arranged in a delta configuration. In other examples, the electrically heated catalyst may include a single heating element.

A process for testing a plurality of components of an exhaust gas aftertreatment system (100) is disclosed, wherein the plurality of components comprises a first SCR catalyst and at least one further SCR catalyst arranged downstream of the first SCR catalyst in the flow direction of exhaust gas to be passed through the exhaust gas aftertreatment system, a first NOx sensor assigned to the first SCR catalyst and at least one further NOx sensor and a first DeNOx element assigned to the first SCR catalyst and at least one further DeNOx element and wherein the process comprises at least the following steps: conditioning the SCR catalysts, testing the NOx sensors, testing the DeNOx systems testing a storage capacity for the reductant of the SCR catalysts.

Methods and systems are provided for an engine of a vehicle. In one example, a method includes activating a heater in response to an engine start request when a catalyst temperature is less than a threshold temperature.

An exhaust gas purifying device for an internal combustion engine includes: an electrically heated catalyst (EHC) including an insulating member; an insulation resistance detector; and a processor. The processor is configured to: acquire an insulation resistance value of the insulating member using the insulation resistance detector each time a trip of the vehicle starts; and execute diagnostic processing to diagnose the state of the EHC when the acquired insulation resistance value is equal to or less than a reference value. In the diagnostic processing, the processor is configured to determine whether or not there is an insulation abnormality of the EHC, based on an index value indicating the degree of decrease in an insulation resistance value of the insulating member of the current trip with respect to an insulation resistance value of the insulating member of one or more past trips including the last trip.