40 CFR § 1068.301 - General provisions for importing engines/equipment.
(b) In general, engines/equipment that you import must be covered by a certificate of conformity unless they were built before emission standards started to apply. This subpart describes the limited cases where we allow importation of exempt or excluded engines/equipment. If an engine has an exemption from exhaust emission standards, this allows you to import the equipment under the same exemption.
(c) U.S. Customs and Border Protection may prevent you from importing engines or equipment if you do not meet the requirements of this subpart. In addition, U.S. Customs and Border Protection regulations may contain other requirements for engines/equipment imported into the United States (see 19 CFR Chapter I).
(d) Complete the appropriate EPA declaration before importing any engines or equipment. These forms may be submitted and stored electronically and are available on the Internet at http://www.epa.gov/OTAQ/imports/ or by phone at 734-214-4100. Importers must keep these records for five years and make them available promptly upon request.
(e) The standard-setting part may define uncertified engines/equipment to be “new” upon importation, whether or not they have already been placed into service. This may affect how the provisions of this subpart apply for your engines/equipment. (See the definition of “new” and other relevant terms in the standard-setting part.)