It is possible that the lender could come after you for the money still owed on the auction. The lender may be able to file a lawsuit against you for the deficiency balance, which is the difference between the amount you still owe on the loan and the amount the car was sold for at auction. If the lender wins the lawsuit, they may be able to garnish your wages or seize your property to satisfy the debt.
If you are concerned about being sued for the deficiency balance, you should contact an attorney to discuss your options. You may be able to negotiate a settlement with the lender or you may be able to file for bankruptcy to discharge the debt.