No, you do not need a corrected W2 if you overcontributed to your 401(k).  You should input the W2 exactly as it appears.

If you haven't done so already, you should click here and follow these instructions to include your excess deferral as wages on your return: Including excess 401(k) contribution on Line 1 of Form 1040.

Note: Currently there is an e-filing issue related to excess 401(K) contributions.  TurboTax is currently working on a solution and an update to fix the issue is expected to be released around 4/5/2019.  

Be sure to sign up for updates to be alerted as soon as there is a solution.  If you do not want to wait for an update, you have the option to paper file your tax returns as this is only an e-filing issue.

You can check out this recently added TurboTax FAQ for more information: Excess 401(k) Contribution Preventing E-filing.