In what situation would a Smog Check be considered a "fail"?

A Smog Check would be considered a "fail" when any required emissions control component is missing, modified, or not functioning. This is critical because the primary purpose of the Smog Check is to ensure that vehicles meet emissions standards set by regulatory authorities to help protect air quality. If essential components, such as catalytic converters, oxygen sensors, or EGR valves, are absent or not working correctly, the vehicle cannot regulate emissions as intended.

This situation leads to increased pollutants being released into the atmosphere, which can significantly impact environmental health and public safety. Consequently, the inspection process specifically flags these deficiencies to ensure compliance with emissions laws, directly correlating to the goal of reducing harmful emissions from vehicles on the road.