When should a vehicle be rejected if the malfunction indicator light is not functioning?

A vehicle should be rejected if the malfunction indicator light is not functioning when the ignition key is turned to "on" with the engine off. This is a critical aspect of vehicle inspections, as the malfunction indicator light (often referred to as the "check engine" light) is designed to illuminate when there is a problem with the vehicle’s engine or emissions control systems.

During the inspection process, testing the light with the ignition in the "on" position, without the engine running, allows inspectors to verify whether the light operates correctly. If it does not illuminate in this position, it indicates a potential failure in the vehicle's onboard diagnostics system, and the vehicle should be rejected until the light is operational.

This specific timing is essential because it ensures that the driver is aware of any potential issues before the vehicle is driven, allowing for timely repairs.