Emission Control Systems: Testing and Inspection

A maintenance reminder light or flag is used to indicate that a specific mileage or period of time has elapsed and a required emission control service must be performed. After the required emission control service has been performed the maintenance reminder light or flag should be reset.

If an emission maintenance reminder flag is present or if the emission maintenance reminder light is continually illuminated while the engine is operating, the vehicle should be suspected of needing a required emission control maintenance service.