Some are having much more success.

Seems that there are 20 DIFFERENT codes, each of which an be used only once. The twitter feed #N9seconds is supposed to show people's guesses.

So far, 8 have been found, of which the 5 I know are:
210611 - date on football player's phone
PRND12 - taxi gears
DCA578 - taxi number plate
MS2173 - da vinci manuscript screw
132545 - watch time in all over design