Yes. If you reported a 401(k) contribution as a Traditional IRA contribution, that would have been a mistake. If you received an IRA deduction on your 1040, you likely will owe back taxes for these years. If you reported a Roth IRA contribution, its unlikely that this impacted your tax reporting. However, its also unlikely that you reported it as a Roth.
Please look at 2015 Form 1040, line 32 to see if there's an IRA deduction. If not, make sure you don't see Form 8606 with your return.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
