2001 Chevy Astro Service Engine Soon Light

it means that the vehicle's computer system has detected a problem with something and stored a trouble code(s). your local auto part store can retrieve the trouble code(s) that are stored for you. post the codes here and I will follow up.

I took the van to the auto parts store and they hooked up the device to the van and came up with code P0446. Something about fuel vapor not burning properly. The car has not behaved differently from before the light came on. What should I do now?

It could be a loose or poorly fitting cover to the air filter, which often follows a quick oil/lube service. Or the vacuum hose that fits to the vent solenoid is loose or off, often from the same type of service. The solenoid and vacuum ports are often attached to the air filter cannister.