Ill. Admin. Code tit. 35 § 207.410
Vehicle scrappage plans may include an evaporative system integrity test to determine the ability of each vehicle's system to recycle vapors. The results of these tests may be used to characterize the functional status of the vehicle's evaporative control system for use as an input to USEPA's MOBILE model. If the applicable vehicle scrappage plan is for a vehicle scrappage project, the evaporative system integrity test administered at an official vehicle emissions test station of the Agency pursuant to 625 ILCS 5/13B-10 must be used to measure evaporative emissions. Vehicle scrappage plans for programs may specify the use of the evaporative system test administered at an official test station of the Agency or the use of another test.
Ill. Admin. Code tit. 35, § 207.410