Directive 2010/26/EU introduced provisions on NO_x control which are necessary to ensure that the sophisticated after treatment systems, required in order to meet the new emission limits for Stage IIIB and IV engines, function properly. In particular, to avoid that operators circumvent compliance with emission limits, it is appropriate to complement the provisions on NO_x control by introducing an operator warning system based on the corresponding provisions of Regulation (EC) No 595/2009 for heavy duty vehicles (euro VI), combined with a two-stage inducement system which reduces significantly the equipment’s performance thus enforcing compliance.

With the introduction of electronically controlled engines it is necessary to adapt the test procedure in order to ensure that engine tests better reflect real use conditions, further preventing circumvention of emission requirements (cycle beating). Therefore, during type approval, compliance should be demonstrated at a working area of the tested engine which has been selected on the basis of the ISO 8178 standard. It is also necessary to specify the engine operating conditions under which those tests are carried out and to modify the calculation methods for specific emissions in order to correspond to those required for heavy duty vehicles (euro VI) and to align them with the provisions of the major trading partners of the Union.

Directive 97/68/EC requires the manufacturer to specify the engine emission performance under specific ambient control conditions relating to altitude or pressure and temperature. In order to better reflect the real use of engines, it is appropriate to extend the temperature/pressure and altitude criteria by aligning the provisions more closely with the requirements for heavy duty euro VI engines.

The durability requirements should also be revised in order to guarantee the efficiency of the emission reduction once the engine is in operation. Due to the technological changes associated with Stage IV engines and their respective after treatment system, the durability provisions laid down in Directive 97/68/EC are not appropriate for those engines, and therefore provisions based on those of Regulation (EC) No 595/2009 regarding heavy duty euro VI engines should be integrated in Directive 97/68/EC.

A globally harmonised test procedure for Stage IV engines has been adopted at the level of the United Nations Economic Commission for Europe (UNECE Regulation No 96.03 series of amendments). It is appropriate to provide that that procedure also applies to the testing of those engines in the Union.

Directive 97/68/EC provides that approvals issued under other specific Union or UNECE legislation are equivalent to type approvals issued under that Directive. The references to the legal acts considered as equivalent should be adapted to current versions in force. With regard to heavy duty euro VI engines it is necessary to specify that the equivalency can only be met if certain additional inducement requirements are respected.

The reporting of carbon dioxide (CO₂) emissions provides further indication about the performance of an engine. Reporting of CO₂ emissions on the engine test cycles is part of the provisions of Regulation (EC) No 595/2009 for heavy duty vehicles (euro VI and Environmental Protection Agency (EPA) 40CFR Greenhouse Gas Emissions Standards). It is therefore appropriate to introduce such provisions also in Directive 97/68/EC.

Directive 97/68/EC does not contain specific requirements for crankcase emissions, which are secondary engine emissions. In order to avoid interpretation problems, it is necessary to clarify how crankcase emissions are taken into account in judging whether the emission test is passed or not. Those provisions should be aligned with Heavy Duty euro VI and US Tier 4 provisions (EPA 40CFR part 1039).

Directive 97/68/EC specifies that engines are categorised in different engine power ranges due to the net engine power and thus emission limit requirements. With new electronically controlled engines, the maximal engine power could be different from the rated engine power. In order to ensure that the emission requirements are met, the engine power to be considered should be the maximum engine power.

The information documents laid down in Directive 97/68/EC should be updated to reflect technical progress and the changes introduced. The new documents should allow a complete reporting.

Directive 97/68/EC should therefore be amended accordingly.

In accordance with the Joint Political Declaration of Member States and the Commission on explanatory documents of 28 September 2011, Member States have undertaken to accompany, in justified cases, the notification of their transposition measures with one or more documents explaining the relationship between the components of a directive and the corresponding parts of national transposition instruments.

The measures provided for in this Directive are in accordance with the opinion of the Technical Committee of Motor Vehicles competent under Article 15 of Directive 97/68/EC,