Section 85.2104 - Owners' compliance with instructions for proper maintenance and use(a) An emission warranty claim may be denied on the basis of noncompliance by a vehicle owner with the written instructions for proper maintenance and use.(b) When determining whether an owner has complied with the written instructions for proper maintenance and use, a vehicle manufacturer may require an owner to submit evidence of compliance only with those written maintenance instructions for which the manufacturer has an objective reason for believing: (1) Were not performed; and(2) If not performed could be the cause of the particular vehicle's exceeding applicable emission standards.(c) Evidence of compliance with a maintenance instruction may consist of: (1) A maintenance log book which has been validated at the approximate time or mileage intervals specified for service by someone who regularly engages in the business of servicing automobiles for the relevant maintenance instruction(s); or(2) A showing that the vehicle has been submitted for scheduled maintenance servicing at the approximate time or mileage intervals specified for service to someone who regularly engages in the business of servicing automobiles for the purpose of performing the relevant maintenance; or(3) A statement by the vehicle owner that he or she performed the maintenance at the approximate time or mileage interval specified including a showing, (i) That the owner purchased and used proper parts, and(ii) Upon request by the vehicle manufacturer, that the owner is able to perform the maintenance properly.(d) The time/mileage interval for scheduled maintenance services shall be the service interval specified for the part in the written instructions for proper maintenance and use. However, in the case of certified parts having a maintenance or replacement interval different from that specified in the written instructions for proper maintenance and use, the time/mileage interval shall be the service interval for which the part was certified.(e) The owner may perform maintenance or have maintenance performed more frequently than required in the maintenance instructions.(f) Written instruction for proper use of battery electric vehicles and plug-in hybrid electric vehicles may identify certain behaviors or vehicle operating modes expected to unreasonably or artificially shorten battery durability. For example, exceeding a vehicle's towing capacity might be considered improper use. However, the manufacturer should not consider actions to be improper use if the vehicle can be designed to prevent the targeted behaviors or operating modes. Evidence of compliance with the requirement to properly use vehicles under this paragraph (f) is generally limited to onboard data logging, though manufacturers may also request vehicle owners to make a statement regarding specific behaviors or vehicle operating modes.(g) Except as provided in paragraph (h) of this section, a manufacturer may deny an emission warranty claim on the basis of noncompliance with the written instructions for proper maintenance and use if and only if:(1) An owner is not able to comply with a request by a manufacturer for evidence pursuant to paragraph (c) or (f) of this section; or(2) Notwithstanding the evidence presented pursuant to paragraph (c) of this section, the manufacturer can prove that the vehicle failed because of any of the following conditions:(i) The vehicle was abused.(ii) An instruction for the proper maintenance and use was performed in a manner resulting in a component's being improperly installed or a component or related parameter's being adjusted substantially outside of the manufacturer's specifications.(iii) Unscheduled maintenance was performed on a vehicle which resulted in the removing or rendering inoperative of any component affecting the vehicle's emissions.(h) In no case may a manufacturer deny an emission warranty claim on the basis of-(1) Warranty work or predelivery service performed by any facility authorized by the vehicle manufacturer to perform such work or service; or(2) Work performed in an emergency situation to rectify an unsafe condition, including an unsafe driveability condition, attributable to the manufacturer, provided the vehicle owner has taken steps to put the vehicle back in a conforming condition in a timely manner; or(3) The use of any uncertified part or non-compliance with any written instruction for proper maintenance and use which is not relevant to the reason that the vehicle failed to comply with applicable emission standards; or(4) Any cause attributable to the vehicle manufacturer; or(5) The use of any fuel which is commonly available in the geographical area in which the vehicle or engine is located, unless the written instructions for proper maintenance and use specify that the use of that fuel would adversely affect the emission control devices and systems of the vehicle, and there is commonly available information for the owner to identify the proper fuel to be used.45 FR 34839, May 22, 1980, as amended at 54 FR 32587, Aug. 8, 1989; 88 FR 4473 , Jan. 24, 2023 88 FR 4473 , 3/27/2023; 89 FR 28153 , 6/17/2024