The penalty for a 16 year old driving without insurance in Minnesota is likely the same as an adult. To be sure check with your department of motor vehicles. Driving without a license in Minnesota can lead to the driver's license being suspended or revoked in addition to being charged fines. In some jurisdictions though the courts will give you time to show proof of insurance and dismiss the stiffer penalties (such as the license revocation).
Your 16 year old should have been put onto your insurance policy as soon as he became licensed. Most all insurance companies request that all licensed members of a household be listed on the policy. So if you have not already added him to your policy or if he needs his own policy we can help you with MN car insurance.