Emission legislation for heavy duty commercial vehicles

This part of the website is dedicated to emission legislation for heavy duty commercial vehicles such as trucks and buses. It covers the legislation such as EURO4, EURO5, and EURO6, but also about expected future legislation (On board diagnostics) and the technologies SCR and EGR. When AdBlue was implemented during EURO4 in 2006 there were many problems in the beginning, we will give you some examples from the beginning.

Other information about AdBlue for Trucks and Buses is available via these links, or the top menu.

Implementation problems of the past

Introduction of AdBlue back in 2005 together with the Euro 4 emission legislation had diverse implementation challenges.

  • Initially the AdBlue tanks in the trucks were not equipped with sensors, to check if the AdBlue tank was filled with AdBlue or with some other fluid. The trucks kept running even though the AdBlue tank was not filled with AdBlue. - Trucks were not equipped with an NOₓ-sensor at the end of the tail-pipe, injection of AdBlue was less controlled which could create cake-forming in the catalyst and thus breakdowns
  • Truck drivers could not find commercial filling sites to fill up the tank with AdBlue. The initial period this was covered by using 20 liter AdBlue cans.
  • There were no spare parts available for the SCR.
  • The quality of the SCR-catalysts was not good enough.

As the standards became stricter with the introduction of Euro 5 a majority of the truck sector started to use SCR, and these problems were solved.

Another problem of the past and for the future is: A general lack of awareness about AdBlue and upholding the Quality or purity of AdBlue.

Even today the public and users of AdBlue consuming machines have a general lack of knowledge about handling and possible problems when using AdBlue incorrectly..

Where could it go wrong:

  • When using dispensing materials which are not specially developed for AdBlue handling. These materials can contaminate AdBlue by slowly dissolving in AdBlue, or getting rusty.
  • When using previous used canisters, jerry cans, or other vessels which could have rest product in them.
  • When using a funnel which is not clean, sand, dust, or for example diesel will contaminate the AdBlue.
  • When using AdBLue produced by non VDA-licensed producers, specification of AdBlue is very strict any deviation on this will harm your vehicle, also products that deviate of the specs are not allowed to be call AdBlue.
  • When people do not use the high specified Automotive non coated Urea and demineralized water for production of AdBlue, the fluid will then be out of AdBlue specifications.
  • When not storing AdBLue correctly,

More information about AdBlue and how to use it can be found in the AdBlue Information section.



Emission Technology

There are two types of technology developed to reduce emission in diesel engines: SCR (Selective Catalyst Reduction) and EGR (Exhaust Gas Regulation). SCR technology uses AdBlue as a NOx reduction fluid. During EURO 4 emission legislation Truck and bus manufacturers could choose between these two technologies, now with EURO 6 legislation in place, almost all manufacturers need to use both technologies to reach the stringent emission criteria. 

What is EGR?

EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. The exhaust gas is mixed with incoming air, which causes the oxygen level of the mixture to drop. Since the oxygen level is now lower than usual, there is more inert gas in the combustion chambers and the generated heat must be spread over more mass. Because the heat is spread, the combustion temperature drops. The nitro oxide (NOₓ) emissions will be reduced since NOₓ is usually formed when a mixture of nitrogen and oxygen is subjected to a high temperature. Because of this EGR-technology the NOₓ emission is reduced by up to 30%. Although Euro 5/V emission standards could be met by EGR technology, Euro 6 standards require the use of Selective Catalytic Reduction and AdBlue. The EGR technology has a large impact on the needed cooling capacity of truck, as high temperature exhaust gasses and inlet air needs to be cooled down before combustion.

What is SCR?

To meet the Euro 6 standards SCR (Selective Catalytic Reduction)-technology is required. SCR-technology reduces the NOₓ emission by converting NOₓ with the help of a catalyst into the far less harmful nitrogen (N₂) and water (H₂O). For this conversion a gaseous reductant must be added in the stream of emission. This gaseous reductant is vaporized diesel exhaust fluid (DEF), or  AdBlue as it is called..

 Other information about AdBlue for Trucks and Buses is available via these links, or the top menu.

Future Legislation OBD (on board diagnosation)

The future of emission legislation will focus mainly on controlling the emissions with the help of On Board Diagnostics (OBD). For future Heavy-Duty-On-Highway OBD regulations 2014 – 2021 there will be much more sensor controlled processes in the trucks and buses.

The developments in on boards diagnostics are not limited to just SCR-systems and the measurement of the reductant quality. For other areas the on board diagnostics are improved too, for example: EGR-catalysts, crank case ventilation, fuel injection and many other areas.

Euro 1 to Euro 6

Commercial vehicles sold in Europe are subject to strict emission limits.. To reduce emission the European Union enforced Euro 1 in 1992 for commercial vehicles. Euro 1 was setting emission standards for commercial vehicles and light trucks. It was the start of a step by step reduction of emissions from all engines to improve air quality in Europe. Euro 1 was soon followed by Euro 2 in 1996, which included legislation for motorcycles. Euro 3 was introduced in the EU in 1999 and limited diesel car emissions. Euro 3 also included legislation for Heavy Goods Vehicles.

Euro 4 was introduced in 2005 and proposed further limiting of petrol and diesel vehicles emissions. In the EURO 4 legislation it stated that the NOX emission limits for heavy duty vehicles were limited to 3.5 g/kWh. This resulted in the use of SCR-technology and thus AdBlue. Exhaust Gas Recirculation (EGR) was the second technology which made NOₓ reduction possible. With Euro 4 the truck manufacturers had different opinions of which of these two technologies was best. Initially there were implications and problems when implementing these technologies. Since AdBlue and SCR- and EGR-technology were new it was hard to get new parts for the systems. The availability of AdBlue was limited throughout Europe, which gave many drivers difficulties. With the Euro 4 technology it was possible to trick the machine by filling up the AdBlue tank with another liquid. However, soon after Euro 4 Euro 5 was developed, which made this misuse impossible.

Euro 5 came in to force in 2009. It proposed to limit harmful emission from trucks and buses even more. The focus is mainly to reduce the emission of nitrogen oxides (NOₓ) from 3.5 g/kWh to 2.0 g/kWh and particulate matter (PM) of diesel powered vehicles. Most commercial vehicle manufacturers resorted to the Selective Catalyst Reduction-system (SCR) to meet the emission standards. Only a few truck brands still use the EGR-technology to reach the emission legislation. If a truck or bus runs without AdBlue the motor management will eventually limit the engine performance.

EURO 6 is the strictest European emission standard up to now. It will especially affect standards for diesel driven vehicles. Compared to Euro 5 Euro 6 focusses on a further decrease of two types of emission: nitro oxide (NOₓ) and particulate matter (PM). Limits are quite strict:

  • NOₓ will be reduced by 80% - up to 0,40 g/kWh (European Stationary Cycle)
  • NOₓ will be reduced by 77% - up to 0,46 g/kWh (European Transient Cycle)
  • PM will be reduced by 50% - up to 0,01 g/kWh

Consequently, all producers need EGR- and SCR-technology to reduce enough NOₓ to reach the emission legislation. The EGR- and SCR-technology work together to reduce the emission to the levels as set in EURO 6. . The SCR and the EGR work together with the DPF and DOC, this makes tampering with the emission after treatment technology difficult and not to be taken lightly. There is a significant possibility this tampering will result in breakdown and downtime of your vehicle.

Euro 6 is mandatory for all new types of heavy duty trucks and buses since 31 December 2012. Since 31 December 2013 Euro 6 is mandatory for all new registrations.