I have a Betterment acct, however, my 1099-B has no "special codes" listed to enter into TurboTax for my Box A & D summaries. Where do I locate these codes? R they needed

If you look at an "official" 1099-B:

https://www.irs.gov/pub/irs-access/f1099b_accessible.pdf

you'll see there's a Box 1g for "adjustments" and a Box 1f for a "code."

Those two boxes are there for the broker's use only.  They are not there for you to "fix" problems with the 1099-B.

IF there is anything in Box 1g THEN there must be a code in Box 1f and the only acceptable codes are:W” and “D”.

So, if you entered something in Box 1g, or the broker, (in error), put something like "$0.00" in there, or even if there's some non-printing characters in there, maybe caused by a bad .TXF file you imported, then TurboTax insists there be a code in Box 1f.

The fix here is to go back to that trade and make sure Box 1g is completely blank.  If that doesn't fix things then completely delete the trade and re-enter it manually, making sure to leave Box 1g blank.

Thank you  for the answer TurboTaxTMDonaldM. The only complication on my end is that I have values in Box 1g but there is no Box 1f on my 1099-B from betterment. Not even the individual transactions have any information about a "code"

Same. 

You may not have any information that belongs in box 1F this is for Accrued Market Discount which often there is no information to report.  If you do not have anything just leave the box blank.