It is illegal for a dealership to repossess a car if the payments have been made on time and in full. However, some dealers may claim that a missed payment is late even if it was received on time as the funds may take a few days to reach the account used to receive payments.
If a dealership attempts to repossess your car even though you have made all of your payments, you should contact an attorney and ask for more time before the repossession.