(a) No new vehicle shall be equipped with a defeat device.

(b) EPA may test or require testing on any vehicle at a designated location, using driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use, for the purposes of investigating a potential defeat device.

(c) For cold temperature CO, NMHC, and NMOG+NOX emission control, EPA will use a guideline to determine the appropriateness of the CO emission control and the NMHC or NMOG+NOX emission control at ambient temperatures between 25 °F (the upper bound of the range for cold temperature testing) and 68 °F (the lower bound of the FTP test temperature range). The guideline for CO and NMOG+NOX emission congruity across the intermediate temperature range is the linear interpolation between the CO or NMOG+NOX standard applicable at 25 °F and the corresponding standard applicable at 68 °F. The guideline for NMHC emission congruity across the intermediate temperature range is the linear interpolation between the NMHC FEL pass limit (e.g., 0.3499 g/mi for a 0.3 g/mi FEL) applicable at 20 °F and the Tier 2 NMOG standard or the Tier 3 or Tier 4 NMOG+NOX bin standard to which the vehicle was certified at 68 °F, where the intermediate temperature NMHC level is rounded to the nearest 0.01 g/mile for comparison to the interpolated line. The following provisions apply for vehicles that exceed the specified emission guideline during intermediate temperature testing:

(1) If the CO emission level is greater than the 20 °F emission standard, the vehicle will automatically be considered to be equipped with a defeat device without further investigation. If the intermediate temperature NMHC or NMOG+NOX emission level, rounded to the nearest 0.01 g/mile or the nearest 10 mg/mile, is greater than the 20 °F FEL pass limit, the vehicle will be presumed to have a defeat device unless the manufacturer provides evidence to EPA's satisfaction that the cause of the test result in question is not due to a defeat device.

(2) If the conditions in paragraph (c)(1) of this section do not apply, EPA may investigate the vehicle design for the presence of a defeat device under paragraph (d) of this section.

(d) The following provisions apply for vehicle designs EPA designates for investigation as possible defeat devices:

(1) The manufacturer must show to EPA's satisfaction that the vehicle design does not incorporate strategies that unnecessarily reduce emission control effectiveness exhibited over the driving cycles specified in this subpart, the fuel economy test procedures in 40 CFR part 600, or the air conditioning efficiency test in 40 CFR 1066.845, when the vehicle is operated under conditions that may reasonably be expected to be encountered in normal operation and use.

(2) [Reserved]

(3) The following information requirements apply:

(i) Upon request by EPA, the manufacturer must provide an explanation containing detailed information regarding test programs, engineering evaluations, design specifications, calibrations, on-board computer algorithms, and design strategies incorporated for operation both during and outside of the Federal emission test procedures.

(ii) For purposes of investigation of possible cold temperature CO, NMHC, or NMOG+NOX defeat devices under this paragraph (d), the manufacturer must provide an explanation to show to EPA's satisfaction that CO emissions and NMHC or NMOG+NOX emissions are reasonably controlled in reference to the linear guideline across the intermediate temperature range.

(e) For each test group the manufacturer must submit an engineering evaluation with the Part II certification application demonstrating to EPA's satisfaction that a discontinuity in emissions of non-methane organic gases, particulate matter, carbon monoxide, carbon dioxide, oxides of nitrogen, nitrous oxide, methane, and formaldehyde measured on the Federal Test Procedure (40 CFR 1066.801(c)(1)) and on the Highway Fuel Economy Test Procedure (40 CFR 1066.801(c)(5)) does not occur in the temperature range of 20 to 86 °F.

[89 FR 28161, Apr. 18, 2024]