The thing not stated in these answers is that once you have entered the 6 digit PIN as other answers explain (in the Other Tax Situations menu), you still have to enter a 5 digit PIN for TT at the end, but it doesn't matter what you enter there. The 6 digit PIN will be used.
BUT another related problem I encountered was not explained. My spouse had gotten a new PIN through the mail and I entered it when asked, the first time through. But I did not know that the IRS had also issued a new PIN to me, and never sent a letter. (Even though I had previously requested mail notifications). I had to go into the IRS website (if you don't have an account that is a hassle) to find my new 6 digit PIN after my e-file was rejected twice.
Apparently if anyone on your return has had a new PIN issued, everyone signatory on your return will need one.
I hope Intuit will fix the field for the PIN to eliminate this confusion and accept the 6 digits.
