Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:110:p31
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 110 (pt 31/59)
Character Range: 691250–694176

component (e.g. sensors and actuators, dosing control unit) of a deNOx system including, when applicable, the reagent heating system, failure of the reagent dosing system (e.g. missing air supply, clogged nozzle, dosing pump failure).

             3.2.3.3. In the case of an engine equipped with a particulate filter, examples of monitoring for major functional failure are for major melting of the trap substrate or a clogged trap resulting in a differential pressure out of the range declared by the manufacturer, any electrical failure of a component (e.g. sensors and actuators, dosing control unit) of a particulate filter, any failure, when applicable, of a reagent dosing system (e.g. clogged nozzle, dosing pump failure).

             3.2.4. Manufacturers may demonstrate to the approval authority that certain components or systems need not be monitored if, in the event of their total failure or removal, emissions do not exceed the applicable thresholds limits for OBD Stage 1 given in the table in Article 4(3) of this Direc- tive when measured over the cycles shown in section 1.1 of Appendix 1 to this Annex. This provision shall not apply to an exhaust gas recir- culation (EGR) device, a deNOx system, a particulate filter or a combined deNOx-particulate filter system nor shall it apply to a component or system that is monitored for major functional failure.

             3.3. OBD Stage 2 requirements

             3.3.1. From the dates given in Article 4(2) of this Directive the OBD system of all diesel or gas engines and of vehicles equipped with a diesel or a gas engine must indicate the failure of an emission-related component or system of the engine system when that failure results in an increase in emis- sions above the appropriate OBD thresholds given in the table in Article 4(3) of this Directive.

              The OBD system must consider the communication interface (hardware and messages) between the engine system electronic control unit(s) (EECU) and any other power train or vehicle control unit when the exchanged information has an influence on the correct functioning of the emission control. The OBD system must diagnose the integrity of the connection between the EECU and the medium that provides the link with these other vehicle components (e.g. the communication bus).

             3.3.2. In satisfying the Stage 2 requirements, the OBD system must monitor for:

             3.3.2.1. reduction in the efficiency of the catalyst, where fitted in a separate housing, that may or may not be part of a deNOx system or particulate filter.

             3.3.2.2. reduction in the efficiency of the deNOx system, where fitted, with respect to the emissions of NOx only.

             3.3.2.3. reduction in the efficiency of the particulate filter, where fitted, with respect to the emissions of particulate only.

             3.3.2.4. reduction in the efficiency of a combined