§ 51.351 Enhanced I/M performance standard.

(a) [Reserved]

(b) On-road testing. The performance standard shall include on-road testing (including out-of-cycle repairs in the case of confirmed failures) of at least 0.5% of the subject vehicle population, or 20,000 vehicles whichever is less, as a supplement to the periodic inspection required in paragraphs (f), (g), and (h) of this section. Specific requirements are listed in § 51.371 of this subpart.

(c) On-board diagnostics (OBD). For those areas required to implement an enhanced I/M program prior to the effective date of designation and classifications under the 8-hour ozone standard, the performance standard shall include inspection of all model year 1996 and later light-duty vehicles and light-duty trucks equipped with certified on-board diagnostic systems, and repair of malfunctions or system deterioration identified by or affecting OBD systems as specified in § 51.357, and assuming a start date of 2002 for such testing. For areas required to implement enhanced I/M as a result of designation and classification under the 8-hour ozone standard, the performance standard defined in paragraph (i) of this section shall include inspection of all model year 2001 and later light-duty vehicles and light-duty trucks equipped with certified on-board diagnostic systems, and repair of malfunctions or system deterioration identified by or affecting OBD systems as specified in § 51.357, and assuming a start date of 4 years after the effective date of designation and classification under the 8-hour ozone standard.

(d) Modeling requirements. Equivalency of the emission levels which will be achieved by the I/M program design in the SIP to those of the model program described in this section shall be demonstrated using the most current version of EPA's mobile source emission model, or an alternative approved by the Administrator, using EPA guidance to aid in the estimation of input parameters. States may adopt alternative approaches that meet this performance standard. States may do so through program design changes that affect normal I/M input parameters to the mobile source emission factor model, or through program changes (such as the accelerated retirement of high emitting vehicles) that reduce in-use mobile source emissions. If the Administrator finds, under section 182(b)(1)(A)(i) of the Act pertaining to reasonable further progress demonstrations or section 182(f)(1) of the Act pertaining to provisions for major stationary sources, that NO_X emission reductions are not beneficial in a given ozone nonattainment area, then NO_X emission reductions are not required of the enhanced I/M program, but the program shall be designed to offset NO_X increases resulting from the repair of HC and CO failures.

(e) [Reserved]

(f) High Enhanced Performance Standard. Enhanced I/M programs shall be designed and implemented to meet or exceed a minimum performance standard, which is expressed as emission levels in area-wide average grams per mile (gpm), achieved from highway mobile sources as a result of the program. The emission levels achieved by the State's program design shall be calculated using the most current version, at the time of submittal, of the EPA mobile source emission factor model or an alternative model approved by the Administrator, and shall meet the minimum performance standard both in operation and for SIP approval. Areas shall meet the performance standard for the pollutants which cause them to be subject to enhanced I/M requirements. In the case of ozone nonattainment areas subject to enhanced I/M and subject areas in the Ozone Transport Region, the performance standard must be met for both oxides of nitrogen (NOx) and volatile organic compounds (VOCs), except as provided in paragraph (d) of this section. Except as provided in paragraphs (g) and (h) of this section, the model program elements for the enhanced I/M performance standard shall be as follows: