What should a vehicle owner do if the 'check engine' light comes on before an emissions test?

When the 'check engine' light comes on, it is an indicator that there is a potential issue with the vehicle’s emissions control system or other critical engine components. Addressing the issue before an emissions test is essential because it ensures that the vehicle is operating properly and efficiently, which can lead to successful passing of the emissions test.

Diagnosing and repairing the issue can correct any faults that may have triggered the warning light, which not only improves the likelihood of passing the test but also enhances the vehicle's performance and overall environmental impact. Ignoring the warning light could lead to a failed emissions test, as the test aims to determine if a vehicle meets emissions standards, and any underlying issues could affect those measurements.

Failing to diagnose the problem or attempting to circumvent it, such as by disconnecting the battery or covering the light, may lead to further complications and ultimately do not resolve the underlying issues that triggered the light. Therefore, having the vehicle diagnosed and repaired is the most responsible and effective action a vehicle owner can take in this situation.