40 CFR 85.2118 - Changes after certification.
The aftermarket part manufacturer shall be required to recertify any part which:
(a) Was certified pursuant to § 85.2114(b) and to which modifications are subsequently made which could affect the results of any test or judgment made that the part meets all of the applicable Emission-Critical Parameters;
(b) Was certified pursuant to § 85.2114(c) and to which modifications are made which are likely to affect emissions or the capability of the part to meet any other requirement of this subpart; or
(c) Was certified and is subsequently modified in a manner affecting the durability of the part or any emission control device, engine or the vehicle upon which such part is installed.