proposed amendment to the on-road vehicle and engine emission regulations on-board diagnostic systems for heavy-duty engines and other amendments 13 pages in english and french the on-road vehicle and engine emission regulations notified under g tbt n can 32 came into effect on january 1 2004. the purpose of these regulations was to establish standards to reduce air pollutants that contribute to smog-forming emissions. the proposed amendments to the on-road vehicle and engine emission regulations are designed to align with the u.s. federal on-board diagnostic obd requirements for heavy-duty engines. on february 24 2009 the united states environmental protection agency u.s. epa published a final rule to extend the obd systems to heavy-duty engines used or intended to be used in heavy-duty vehicles that have a gross vehicle weight rating gvwr of more than 6 350 kg which include minibuses school buses road tractors and dum trucks. while the majority of heavy-duty vehicles and engines sold in canada would likely already comply with u.s. epa standards it is important to recognize that some of these vehicles or engines sold in canada may not. the proposed amendments add the requirement that the heavy-duty engines of the 2013 and later model years used or intended to be used in heavy-duty vehicles that have a gvwr of more than 6 350 kg be equipped with an on-board diagnostic system that conforms to the standards applicable to engines of that model year set out in section 18 of subpart a of the code of federal regulations cfr of the united states. this approach seeks to ensure that the specified standards remain identical in both countries. therefore the proposed amendments would create a level playing field for companies supplying the north american market with heavy-duty vehicles and engines. at the domestic level the proposed amendments would ensure that all manufacturers importers and operating distributors comply with the same standards. the proposed amendments also make administrative changes to the regulations that are intended to ensure consistency between the english and french versions of the regulations and to provide greater clarity to existing provisions.