40 CFR §85.501

1. (a)This subpart describes the provisions related to an exemption from the tampering prohibition in Clean Air Act section 203(a) (42 U.S.C. 7522(a)) for light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, heavy-duty vehicles, and heavy-duty engines. This subpart F does not apply for highway motorcycles or for nonroad or stationary engines or equipment.
2. (b)For purposes of this subpart, the term “you” generally means a clean alternative fuel conversion manufacturer, which may also be called “conversion manufacturer” or “converter”.