Check engine light

00 4Runner - check engine light came on after 60,000 miles; outside of this no problems. The truck appears to be running correctly, but I think that it has to do with the gas cap. How long should I wait to see if it will go off?

it won't goes off. as i know it has to be resetted from the computer inside of your car. mine 4runner and pathfinder had the same problems. i sent them to the dealer to replace the oxygen sensors. they did reset the warning light for me.

Some error codes will reset without external manipulation if they don't reoccurr after some period of time.