It’s strange the dealership had your minor son sign any contract, especially as a cosigner, but according to Nebraska statute 43-2101, a minor cannot enter into a binding contract or be held legally responsible for said contract.
This means that the contract is void and unenforceable for your son. To find out what to do next and see if you are still legally responsible for your part or if an entirely new agreement has to be signed, you should contact the lender.
Jerry shops for low prices with over 50 different insurance companies like Travelers, Nationwide, and Progressive for free. You will get quotes in seconds, can make changes at any time, and if you ever have any questions, agents are just a text away!