40 CFR § 86.1908 - How must I select and screen my in-use engines?
(a) Once we direct you to do testing under this subpart, you must make arrangements to select test vehicles and engines that meet the following criteria:
(1) The engines must be representative of the engine family.
(2) The usage of the vehicles must be representative of typical usage for the vehicles' particular application.
(3) The vehicles come from at least two independent sources.
(4) The key vehicle/engine systems (e.g., power train, drive train, emission control) have been properly maintained and used.
(5) The engines have not been tampered with, rebuilt or undergone major repair that could be expected to affect emissions.
(6) The engines have not been misfueled. For example, an engine may be considered misfueled if operated on a biodiesel fuel blend that is either not listed as allowed or otherwise indicated to be an unacceptable fuel in the vehicle's owner or operator manual.
(7) The engines do not have an illuminated MIL or stored OBD trouble code that lead you to reject the vehicle from the test program as described in § 86.1910(b)(2).
(8) The vehicles are likely to operate for at least three hours (excluding idle) over a complete shift-day, as described in § 86.1910(g).
(10) The vehicle has appropriate space for safe and proper mounting of the PEMS equipment.
(b) You must keep any records of a vehicle's maintenance and use history you obtain from the owner or operator, as required by § 86.1925. You must report the engine's maintenance and use history and information related to the OBD system, as described in § 86.1920.
(c) You must notify us before rejecting a candidate vehicle for reasons other than failing to meet the acceptance criteria in paragraph (a) of this section. A candidate vehicle is any prospective vehicle you have identified to potentially fulfill your testing requirements under this subpart. Include your reasons for rejecting each vehicle. If an owner declines to participate in the test program, you may reject the vehicle without prior notification. Such a rejection must be reported as described in § 86.1920. We may allow you to replace the rejected vehicle with another candidate vehicle to meet your testing requirements for the specific engine family.
(d) You must report when, how, and why you reject candidate vehicles, as described in § 86.1920.