Mexico: Nonroad Engines

Regulation NOM-174-SEMARNAT-2026

Emission regulations for new nonroad engines were first published in May 2026 and took effect November 2026. The regulations, NOM-174-SEMARNAT-2026, apply only to variable speed diesel engines rated from 19 to 560 kW and require compliance with US EPA Tier 3 or EU Stage IIIA emission limits. Engines intended for electricity generation, locomotives, railway equipment, vessels, aircraft and agricultural machinery are excluded [6323].

Importers or manufacturers of EPA Tier 3/EU Stage IIIA compliant engines must obtain a NOM Certificate issued by the Federal Attorney for Environmental Protection which certifies that new engines comply with NOM-174-SEMARNAT-2026. Alternatively, for engines meeting US EPA Tier 4 final and EU Stage IIIB and Stage IV emission limits, certification requirements are simplified and certification documents issued outside of Mexico appear to be sufficient.