40 CFR § 85.2103 - Emission performance warranty.
(a) The manufacturer of each vehicle to which this subpart applies shall warrant in writing that if:
(1) The vehicle is maintained and operated in accordance with the written instructions for proper maintenance and use and
(2) The vehicle fails to conform at any time during its useful life to the applicable emission standards or family emission limits as determined by an EPA-approved emission test, and
(3) Such nonconformity results or will result in the vehicle owner having to bear any penalty or other sanction (including the denial of the right to use the vehicle) under local, State or Federal law, then the manufacturer shall remedy the nonconformity at no cost to the owner; except that, if the vehicle has been in operation for more than 24 months or 24,000 miles, the manufacturer shall be required to remedy only those nonconformities resulting from the failure of any of the specified major emission control components listed in 42 U.S.C. 7541(i)(2) or components which have been designated by the Administrator under 42 U.S.C. 7541(i)(2) to be specified major emission control components until the vehicle has been in operation for 8 years or 80,000 miles.
(b) The warranty period shall begin on the date the vehicle is delivered to its ultimate purchaser, or if the vehicle is first placed in service as a “demonstrator” or “company” car prior to delivery, on the date it is first placed in service.