What should a vehicle owner do if the "check engine" light is illuminated prior to an emissions test?

Having the vehicle diagnosed and repaired before testing is essential because an illuminated "check engine" light often indicates that the vehicle's emission controls may be malfunctioning. This can lead to the vehicle failing the emissions test. Diagnosing and addressing any issues can help ensure that the vehicle operates within the required emissions standards and improves air quality. Furthermore, an emissions test is likely to fail if the check engine light is on, since it signals that the vehicle's onboard diagnostic system has detected a problem that could affect emissions. Taking proactive steps by conducting repairs before the emissions test can save time, money, and the hassle of retesting.