Should the 511190 Business Activity Code work? It is not listed within the TurboTax Business software but I've used it in previous years. Anyone else have this problem?

Never mind - I found the answer - the code has changed.

Code 511190 isn't listed among the valid Principal Business or Professional Activity Codes reflected in the IRS' Instructions for Schedule C (Form 1040). 

You can find another appropriate code in the instructions.

Or, on the Enter Your Business Code screen in TurboTax, you can select Lookup Business Codes, enter some relevant keywords that describe your business (for example, day care, bookkeeping, or door-to-door), and then select Search.