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Emissions from diesel and gas engines (up until 2013)

The harmonisation of the technical requirements for emissions from diesel * and gas * engines helps the European Union (EU) to improve air quality.


Directive 2005/55/EC of the European Parliament and of the Council of 28 September 2005 on the approximation of the laws of the Member States relating to the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines for use in vehicles, and the emission of gaseous pollutants from positive-ignition engines fuelled with natural gas or liquefied petroleum gas for use in vehicles [See amending acts].


Directive 2005/55/EC lays down limit values for emissions of gaseous and particulate pollutants and for the opacity of exhaust fumes, compliance with which is a condition for the approval of diesel * and gas * engines and vehicles equipped with these engines. It thus helps to achieve the Community objective of improving air quality, in the interests of protecting the environment and public health.

Emissions of gaseous pollutants and particulate pollutants, opacity of fumes

Initially, the limit values in row B1 of the tables in Annex I, point 6.2.1 of the Directive were applicable to all new types of vehicles and engines from 1 October 2005 and to all new vehicles and engines from 1 October 2006.

In a second phase, the stricter limit values in row B2 of the same tables will be compulsory for all new types of vehicle and engine from 1 October 2008 and then for all new vehicles and engines from 1 October 2009.

Durability of emission control systems

Car manufacturers must also guarantee that diesel and gas engines, having met the standards laid down in Directive 2005/55/EC upon approval, comply with these standards throughout the normal life of the vehicle under normal conditions of use.

Onboard diagnostic systems

Diesel and gas engines, and vehicles fitted with them, must also have an onboard diagnostic system (OBD) which signals immediately any malfunction of the system for checking emissions from the engine once the limit values are exceeded.

Fiscal incentives

Member States are allowed to offer incentives to accelerate the sale of vehicles which meet the conditions of this Directive, as long as these incentives do not distort the internal market.


The Directive applies to polluting emissions from private cars (category M, not including category M1 vehicles weighing less than 3.5 tonnes) and commercial vehicles (category N) fitted with diesel or gas engines.


To create more clarity, at the introduction of the new limit values for polluting emissions, Directive 2005/55/EC repeals and replaces Directive 88/77/EEC. It fits within the framework of the EC approval procedure.

Key terms used in the act
  • Diesel engine: engine which uses the compression ignition principle.
  • Gas engine: engine which runs on natural gas (NG) or liquefied petroleum gas (LPG).


Act Entry into force Deadline for transposition in the Member States Official Journal
Directive 2005/55/EC 9.11.2005 08.11.2006 OJ L 275, 20.10.2005
Amending act(s) Entry into force Deadline for transposition in the Member States Official Journal
Directive 2005/78/EC 19.12.2005 08.11.2006 OJ L 313, 29.11.2005
Directive 2006/51/EC 10.6.2006 08.11.2006 OJ L 152, 7.6.2006
Last updated: 06.05.2007
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