How are improper emissions reflected during a vehicle inspection?

Improper emissions are directly reflected during a vehicle inspection by either failing the emissions test or having a check engine light illuminated. A check engine light is an indicator that the vehicle's onboard diagnostic system has identified an issue related to emissions or other systems. When the light is on, it suggests that there is a potential problem that could lead to higher emissions or the vehicle failing the emissions test.

Failing the emissions test indicates that the vehicle exceeds the permissible levels of harmful pollutants, which is a clear sign of improper emissions control. Various issues, such as a malfunctioning catalytic converter, fuel system problems, or exhaust leaks, can lead to higher emissions. Therefore, either of these conditions—an active check engine light or failing the emissions test—serves as a clear indication of improper emissions and would typically result in a vehicle not passing the inspection.

The other choices do not accurately represent the situation regarding improper emissions. A functioning check engine light would indicate that there is no current fault, which contradicts the notion of improper emissions. Passing the emissions test without issues confirms that the vehicle meets the standards, while visible smoke during an emissions check points to specific problems but is not an official measure like the test results or the check engine light status.