TurboTax makes no assumption that code AA in box 12 of your W-2 has anything to do with a Roth IRA. TurboTax only treats as Roth IRA contributions amounts that you explicitly enter as Roth IRA contributions under Deductions & Credits.
If TurboTax is indicating that you made an excess Roth IRA contribution, either you entered one under Deductions & Credits or your previous year's tax return had an excess Roth IRA contribution that transferred into the tax return that you are currently preparing. IF you entered a Roth IRA contribution under Deductions & Credits and did not actually make a Roth IRA contribution, go back and remove that entry that you made.
