Often referred to as an I/M (Inspection/Maintenance) program, the program is used in numerous states and areas as required by the Environmental Protection Agency to improve air quality. Some states run centralized programs that have state-contracted test stations exclusively dedicated to testing. Other states run decentralized programs, where emissions can be tested at local repair facilities.
I/M programs evaluate emissions from vehicles. This way vehicles can be identified when they are polluting beyond the limits established for certain model years of vehicles. These programs also advocate proper maintenance to prevent high emissions due to maintenance neglect.
Instead of waiting for an emission test that your vehicle could possibly fail, you should be taking your vehicle in for regular maintenance checks, especially if the check engine light or the service engine soon light turns on.