I doubt it. It sounds like you probably are your son's guarantor. The whole idea of the guarantor is that the bank has someone to go after if the main borrower doesn't pay. I don't know what the agreement says, but I'll bet it gives the bank the right to repossess the vehicle for non-payment, and then to come after you for the difference between the reasonable value of the vehicle and the amount left on the loan.
I'm not licensed in Massachusetts so that's not legal advice, just information based on general principles of law which is intended to educate. If you need legal advice, please consult a lawyer who holds Massachusetts licensure.
Until the loan is paid, you are responsible. That was the agreement when you co-signed the loan. If the payments stop, the loan will go into default, and the vehicle will likely be repossessed. Consider speaking to an attorney to advise you of your specific rights, but be prepared for the collectors to pursue you as well.
DISCLAIMER: This answer is provided in response to a "hypothetical" question and provided for general, informational purposes and does not create an attorney/client relationship. The information presented is not legal advice and may change based additional information and research. It is recommended that you speak to an attorney to discuss your specific legal issues.
