No. An individual's participation in an employer-sponsored plan (including a 401(k) plan) does not affect his or her ability to make a contribution to a Traditional IRA. The participation in an employer-sponsored plan may, however, affect the individual's ability to deduct the Traditional IRA contribution. For an individual who is an active participant, the ability to deduct a Traditional IRA contribution is determined by his or her tax-filing status (i.e., married filing jointly, separately, or filing single) and adjusted gross income.
(For information about an individual's ability to deduct a Traditional IRA contribution, see Traditional IRA Deductibility Limits.)
This question was answered by Denise Appleby