Is this an IRA or 401K contribution?

If this is a 401k contribution, you do not need to enter the contribution in the program as there is no deduction allowed.  If there is an excess contribution deferral you need to handle, see the link here.  I am posting a link from MinhT1 for your reference: https://ttlc.intuit.com/community/taxes/discussion/excess-401k-contribution-and-corrected-w-2c-form/...

If this is an IRA contribution, which is allowed for a deduction.  However, the $19,000 seems over the limit.  See IRS link here: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-ira-contribution-li... You might end up paying penalty for the excess contribution.  

@ronlavine

If the $19,000 is reported in box 12 of a W-2, enter amounts in box 12 of your W-2 only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax.  This is not an IRA contribution.

Thanks for trying to help me. But I am self-employed and a 401k contribution is deductible. And the turbotax program solicits me to enter it. But then when the program performs a review it asks me to change the number because the maximum I an deduct is $19,000. However, the amount I'm trying to deduct is $19,000

Thanks for trying to help, but your response is off the mark. I'm self-employed and don't receive a W-2. The contribution is a contribution I've made on my own behalf.

I had a typo in my earlier reply, it should have said, "If the $19,000 is reported in box 12 of a W-2 ..."  Some self-employed also have another employer and make 401(k) contributions there.  It's quite common for people to mistake a 401(k) for an IRA and try to enter their 401(k) contributions as IRA contributions.

Exactly what is the error message you are seeing?

When the program does a final error check, it flags my 401k contribution entry as an error and sends me back to the page on which I enter my 401k contribution in order to correct it.  Turbo Tax says "the total contribution can't exceed $19,000." But my contribution doesn't exceed $19,000. I'm trapped in an endless loop and can't move forward.

This error message may be suggesting that you've not only entered the $19,000 as a 401(k) elective deferral but have also entered some amount as a Roth 401(k) contribution.  When that's the case, TurboTax flags the elective deferral as exceeding $19,000 when it's actually the sum of the elective deferral and the Roth contribution that exceeds $19,000.

 You could very well be right. And in that case it's a software error they should correct. I've already got a support ticket going with them and they've got a team investigating the snafu.