Mexico

Regulatory Background

Mexican emission requirements for new vehicles and engines are adopted by the Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT). Emission compliance is generally required with either the US or European emission standards.

Emission and fuel regulations are published as Mexican standards—Norma Oficial Mexicana (NOM). Typically, the same NOM standard number covers a given vehicle category (for example, NOM-042 for light-duty vehicles or NOM-044 for heavy-duty diesel engines), with revisions indicated by the year of publication.

Regulated Engines and Vehicles

Emission regulated categories of engines and vehicles include:

• Light-duty vehicles (passenger cars and light commercial vehicles),
• Heavy-duty truck and bus engines, including engines fueled by diesel, gasoline and gaseous fuels.

Until 2026, emissions from non-road mobile machinery were unregulated in Mexico. US EPA Tier 3/Euro Stage IIIA limits for some diesel engines between 19 and 560 kW took effect in November 2026 [6323].