Due to varying state, federal, and provincial regulations, specific emission control equipment may vary by area of sale. The U.S. emission equipment is divided into two categories: California and Federal. In this section, the term "California'' applies only to cars originally built to be sold in California. Some California emissions equipment are not shared with equipment installed on cars built to be sold in the other states. Models built to be sold in Canada also have specific emissions equipment, although in many cases the Federal and Canadian equipment are the same.
Both carbureted and fuel injected cars require an assortment of systems and devices to control emissions. Newer cars rely more heavily on computer (ECM) management of many of the engine controls. This eliminates many of the vacuum hoses and linkages around the engine. Remember that not every component is found on every car.