Smog Check Manual – Visual Inspection Practice Test

The key idea is that the visual inspection requires the emission-control system to be complete and intact. If any emission-control component is compromised—damaged, loose, missing, or disconnected—the system could fail to reduce pollutants, so the vehicle fails the VI. This is why the correct answer is that the overall VI fails if any emission-control component is compromised. The other options don’t fit because the standard isn’t about passing when most parts are fine or only reacting to major leaks; it also doesn’t allow ignoring compromised components because damage might be cosmetic. The rule is clear: keep every part of the emission-control system secure and functional to pass.