(a) The Administrator may require that engines or vehicles of a specified configuration be selected in a manner consistent with the requirements of § 86.1110-87 and submitted to him at such place as he may designate for the purpose of conducting emission tests in accordance with § 86.1111-87 to determine whether engines or vehicles manufactured by the manufacturer conform with the regulations of this subpart.

(b)(1) Whenever the Administrator conducts a test on a test engine or vehicle or the Administrator and manufacturer each conduct a test on the same test engine or vehicle, the results of the Administrator's test will comprise the official data for that engine or vehicle.

(2) Whenever the manufacturer conducts all tests on a test engine or vehicle, the manufacturer's test data will be accepted as the official data, provided that if the Administrator makes a determination based on testing under paragraph (a) of this section that there is a substantial lack of agreement between the manufacturer's test results and the Administrator's test results, no manufacturer's test data from the manufacturer's test facility will be accepted for purposes of this subpart.

(c) If the Administrator determines that testing conducted under paragraph (a) of this section demonstrates a lack of agreement under paragraph (b)(2) of this section, the Administrator shall:

(1) Notify the manufacturer in writing of his determination that the manufacturer's test facility is inappropriate for conducting the tests required by this subpart and the reasons therefore; and

(2) Reinstate any manufacturer's data only upon a showing by the manufacturer that the data acquired under paragraph (a) of this section was erroneous and the manufacturer's data was correct.

(d) The manufacturer may request in writing that the Administrator reconsider his determination in paragraph (b)(2) of this section based on data or information which indicates that changes have been made to the test facility and that these changes have resolved the reasons for disqualification.