I am working on Self-Employed online. https://ttlc.intuit.com/questions/4714275-resolved-error-in-review-elective-deferrals-is-more-than-the-allowed-18500-for-401k-plan

[Rachel_W]

If you are encountering a problem trying to e-file your return due to an Excess 401(K) Contribution, it was just announced that an update is currently planned for April 12th, 2019 to resolve this issue. 

You may still see a warning about the excess contribution, but you should be able to e-file.  You can check out this TurboTax FAQ for more information: Excess 401(k) Contribution Preventing E-filing.