You never pay taxes on a loan from a 401k as long as you are still employed and are paying it back through payroll deductions. If you leave the employer, you must pay the balance in full within 60 days or it will be counted as a withdrawal and you will get a 1099-R and must report that as a distribution.
Did you get a 1099-R? What is the code in box 7? If you did not get a 1099-R because you are still in repayment, why do you think you are paying taxes?