You have to spend $715 at a shop licensed by them to do the work. You can't take it to any shop and you can't prove it will cost more than $715. What you can do is prove you live in poverty and they will waive all of it.
Repair Cost Limits
The limit is $75 for 1967 and older vehicles and $715 for 1968 and newer vehicles. Cost limits apply to all vehicles regardless of whether they failed the idle test or the I/M 240 test. However, these limits do not apply if the vehicle failed for visible smoke or missing emissions control equipment.
You may be eligible for a waiver if you have reached the spending limit and your vehicle still won't pass the emissions test. Hardship waivers are also available. Call the Division of Motor Vehicles Emissions Office, 303-205-5603, to inquire about waivers.
How To Find High Quality Repairs
Emissions Repair Guide
If your vehicle fails its emissions test, you are given some helpful materials, including a booklet called the Emissions Repair Guide. This booklet will help you identify a repair shop in your area that has had success correcting emissions-related problems.
If you do not receive this booklet, or misplace it, you may obtain another at any Envirotest-operated Air Care Colorado emissions testing station. You may also call the Air Care Colorado hotline at 303-456-7090 and ask to have the appropriate pages for your area faxed to you.
Each repair facility listed in the booklet has agreed to be rated on its emissions repair performance. The booklet is organized alphabetically by city or town for easy reference. Each listed facility includes address, phone number, credentials, and emissions repair training information. Most importantly, each shop is given a grade that reflects its success in repairing emissions failures on its first attempt. The booklet is updated quarterly, and the scores are weighted to reflect recent repairs. About 25 to 30 percent of the Denver area shops have agreed to be placed in the booklet.
You do not have to use a repair facility listed in this booklet. It has been prepared for your convenience only. You may choose your own repair technician. However, if you fail the retest and decide to apply for a waiver, only part costs will count towards the repair cost limits ($715 for 1968 and newer vehicles, $75 for 1967 and older vehicles).
Finding a Qualified Repair Technician
Ask these questions when selecting a repair technician:
Have you taken emissions repair training classes?
How much specialized training have you had in I/M 240 emissions repair procedures for 1982 and newer vehicles?
Are you listed in the Air Care Colorado Emissions Repair Guide? What is your repair effectiveness score?
Are you certified under Automotive Service Excellence? In which categories?
Are you a member of the Automotive Service Association or other similar professional organizations? Which ones?