Mexico published NOM-044-SEMARNAT-2017, an update to heavy-duty emissions standards, on February 19, 2018. The regulation allows for compliance with A standards, allowing either U.S. 2004 or Euro IV equivalent standards, until June 30, 2019. The regulation introduced new AA and B standards on January 1, 2019. The option for compliance with AA standards, allowing equivalence with either Euro V or U.S. 2007, ends on December 31, 2020. The B standard, allowing equivalence with either Euro VI or U.S. 2010, remains in place indefinitely.
Due to the COVID-19 emergency, a one-year extension was granted on November 11, 2020, which will continue to allow both current standards (Euro VI or U.S. 2010 and Euro V or U.S. 2007) until December 31, 2021.
Conventional pollutant emission limits
Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT)
New on-road vehicles and engines for units above 3,857 kg of gross vehicle weight
The standard NOM-044-SEMARNAT-2006, adopted in 2006 as an update to NOM-044-SEMARNAT-1993, established emission limits for total hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particles, and opacity for new heavy-duty diesel engines. The standard allowed compliance with either US 2004 or Euro IV equivalent standards from in July 2008 through June 2011. An Acuerdo (agreement) from SEMARNAT extended the regulatory timeline for compliance to June 2014, with a second acuerdo adopted in June 2014 extending the timeline indefinitely. A proposed modification to the standard was adopted in December 2014, requiring compliance with US 2010 or Euro VI equivalent standards starting January 1, 2018. The final revision, NOM-044-SEMARNAT-2017, was adopted in February 2018. Although the final version of NOM-044-SEMARNAT-2017 was adopted in February 2018, a one-year extension to the original timeline was granted on November 11, 2020 due to the COVID-19 emergency. The world-class standards of Euro VI or US 2010 are to be exclusively required starting in 2022.
Both NOM-044-SEMARNAT-2006 (diesel) and NOM-076-SEMARNAT-2012 (gasoline) are applicable to new engines intended for use in vehicles with a gross vehicle weight greater than 3,857 kg (8,500 lbs.) or for new vehicles of this size.
Diesel Engine Standards
2018 to present
The revised standard, NOM-044-SEMARNAT-2017 sets A, AA, and B standards for heavy-duty engines and complete heavy-duty vehicles with a gross vehicle weight above 3,857 kg. The following table shows the timing and equivalent standards under U.S. or European regulations.
|Timing and alignment of NOM-044-SEMARNAT-2017|
|Heavy-duty engines||Complete vehicles|
|Implementation||NOM-044||Aligned standard||NOM-044||Aligned standard|
|Until June 30, 2019||1A||U.S. 2004||3A||California LEV I|
|2A||Euro IV||4A||Euro 4|
|January 1, 2019—December 31, 2020||1 AA||U.S. 2007||—||—|
|2 AA||Euro V||4AA||Euro 5|
|From January 1, 2019||1 B||U.S. 2010||3B||U.S. 2010|
|2 B||Euro VI||4B||Euro 6|
Limit values for heavy-duty engines are shown in the following tables. Limits are set in grams per brake horsepower-hour (g/bhp-hr) for U.S.-aligned standards and in grams per kilowatt-hour (g/kWh) for Euro standards. Particle number and ammonia (NH3) limits are set as part of the Euro VI standards but have not been defined as limit values under EPA standards.
|Emissions limits for heavy-duty engines|
|Aligned standard||Standard||Test Cycle||CO||NOx||NMHC||NMHC + NOx||PM||Particle number||NH3|
|U.S. 2004||1A||SET & FTP||15.5||—||—||2.4||0.10||—||—|
|U.S. 2007||1AA||SET & FTP||15.5||1.2||0.14||—||0.01|
|U.S. 2010||1B||SET & FTP||15.5||0.20||0.14||—||0.01||—||—|
|Aligned standard||Standard||Test Cycle||CO||NOx||NMHC||HC||PM||Particle number||NH3|
|Euro VI||2B||WHSC||1.5||0.4||—||0.13||0.01||8.0 x 1011||10|
|WHTC||4.0||0.46||—||0.16||0.01||6.0 x 1011||10|
The useful life requirements for heavy-duty engine standards are as follows. Useful life is defined as the reference values used in durability tests as part of new engine or vehicle certification for design and testing of emission control systems. Useful life does not refer to, nor is it equivalent to, the manufacturer warranty or in-use vehicle emissions.
|Useful life requirements for heavy-duty engines|
|Aligned standard||Standard||Gross vehicle weight (kg)||Useful life|
|Distance (km)||Time (years)|
|U.S. 2004, U.S. 2007, and U.S. 2010||1A, 1AA, and 1B||3,857 – 8,845||177,023||10|
|8,846 – 14,970||297,721|
|14,971 and greater||700,046|
|Euro IV and
|2A and 2AA||3,857 – 15,999||200,000||6|
|16,000 and greater||500,000||7|
|Euro VI||2B||3,857 – 15,999||300,000||6|
|16,000 and greater||700,000||7|
The standard includes optional alternative certification limits for medium-duty complete vehicles.
|Emissions limits and useful life requirements for complete vehicles|
|Aligned standard||Standard||Gross vehicle weight (kg)||Test cycle||CO||NOx||NMHC||PM||Particle Number (#/km)||Useful Life|
|California LEV I||3A||3,857 – 4,539||FTP 75||—||0.311||0.121||0.037||—||193,121||11|
|4,540 – 6,350||—||0.435||0.143||0.037||—|
|U.S. 2010||3B||3,857 – 4,539||FTP 75||—||0.124||0.121||0.012||—||193,121||11|
|4,540 – 6,350||—||0.249||0.143||0.012||—|
|Aligned standard||Standard||Reference weight (kg)||Test cycle||CO||NOx||HC+NOx||PM||Particle Number (#/km)||Useful Life|
These limits can be used for medium-duty vehicles that are certified as complete vehicles, with testing done on a chassis dynamometer, rather than certified as an engine, with testing on an engine dynamometer. The 3B and 4B pathways for certification of complete vehicles were included in the original proposal, while 3A, 4A, and 4AA were added in the final standard.
On-Board Diagnostics and Compliance Inducements
The final standards require full OBD systems to be installed and operating on new vehicles meeting B standards. The type of OBD system must be listed in the certification documentation. Appendix A includes general OBD system requirements and a detailed description of the requirements—including monitoring thresholds and the systems and metrics to monitor—for OBD systems meeting the Euro VI and U.S. 2010 standards. As both U.S. and Euro standards require the full phase-in of OBD systems implementation of B standards, certification documentation under U.S. and Euro standards is used as the primary proof of compliance with OBD requirements.
The regulation requires that all vehicles meeting AA and B standards that are equipped with SCR systems (which require use of DEF for proper control of NOx) are equipped with the full suite of operating systems of alerts and driver inducements to ensure the correct functioning of these systems. These fail-safes include lights, auditory alarms, and requirements to safely limit vehicle operation in all cases of improper use, including lack of DEF, poor-quality DEF, and insufficient consumption or dosing of DEF. Both European and U.S. systems described in Appendix B also include anti-tampering mechanisms to ensure that users do not evade these requirements.
Emission standards for new heavy-duty diesel engines first became effective in model year 1993 and were based on US 1991 and later requirements, including the US Environmental Protection Agency (EPA) FTP transient test cycle. Standards for MY 1993-1998 were equivalent to US standards and compliance could be demonstrated through certification by US EPA. Under NOM-044, engines in Mexico are provided compliance options and can meet European standards, as measured on the official European test cycles (ETC and ESC), as an alternative to the EPA-based standards; compliance with standards can be demonstrated through:
- Letter or proof issued by motor manufacturer, including earnings report issued by the testing laboratory,
- Certificate or proof issued by the Environmental Protection Authority of the country of origin or country of certification, or
- Certificate issued by Certification Bodies for the country of origin or country of certification.
In 2006, the standard NOM-044-SEMARNAT-2006 was adopted, establishing emission limits for total hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particles, and opacity for new heavy-duty diesel engines. The standard allowed compliance with either US 2004 or Euro IV equivalent standards. The emission standards compliance timeline and equivalent limit values of the 1993 and 2006 standards are outlined below:
|1993||US EPA 1991|
|1994||US EPA 1994|
|1998||US EPA 1998|
|2006-2008||US EPA 1998 or Euro III|
|2008†||US EPA 2004 or Euro IV|
|Notes:† extended indefinitely.|
|Smoke opacity %
|Smoke opacity %
|Standard||Test Method||HC||NMHC||CO||NOx||Part||Smoke Opacity3|
Gasoline, LPG, and NG Engine Standards
Emission standards for new heavy-duty engines fueled by gasoline, LPG, natural gas and other alternative fuels are specified by the NOM-076 standard, adopted in 1995, with later amendments in 2012. Similar to the diesel regulations, the emission standards are applicable to gas engines used in vehicles of GVW > 3,857 kg (8,500 lbs).
Gasoline and gaseous fueled engines are tested over the FTP transient test and must meet the US EPA-based emission standards shown in the following 2 tables.
|A1||3,857kg ≤ GVW ≤ 6,350kg||1.1||N/A||14.4||4.0||3.0|
|B2||3,857kg ≤ GVW ≤ 6,350kg||N/A||0.14||14.4||0.2||1.75|
Natural gas engines can alternatively be tested over the European Transition Cycle; relevant standards are show in the following table.
Manufacturers may choose to certify gasoline and gaseous fueled vehicles with GVW up to 6,356 kg (14,000 lbs) on a chassis dynamometer over the FTP-75 cycle. The table below summarizes emission standards for chassis-certified vehicles.
|A||3,857 – 4,536 kg||0.285||3.418||0.807||3.0|
|4,537 – 6,356 kg||0.372||4.350||1.243||3.0|
|B||3,857 – 4,536 kg||0.121||3.977||0.124||1.75|
|4,537 – 6,356 kg||0.142||4.536||0.248||2.30|