You will need to drive your Chevy Silverado for at least 200-300 miles over the course of a few days in order to reset the Emission Monitors (also known as Readiness Flags). Emission monitors are internal self tests which your Silverado's engine control computer needs to conduct to ensure that all the emission systems are functioning properly. Without the monitors in READY or COMPLETE status, your Chevy truck will not be able to pass the smog check.
If your scan tool has a function to display the status of the engine monitors, you'll be able to see when the truck is ready to get the smog inspection. The only monitor as of the time of this post which is allowed to be incomplete is the EVAP monitor.
