The teen was taken into custody, then given a citation to appear in court and released to his parents.
The incident happened Tuesday around 3:20 p.m. when San Bernarardino County sheriff's deputies made a traffic stop in the 3100 block of North Del Rosa Avenue, in an unincorporated county area near San Bernardino.
They say they found 40 pounds of a substance that was believed to be meth inside the 2006 Honda Accord.
The unidentified male juvenile, a Fontana resident, will face a charge of possession of narcotics with intent to sell.