The codes don't work like that, they are a code that gives the ecu the correct injection quantity, it then uses this code and determines a set wear rate, so basically an injector should be coded when first put in and then never be recoded.

these codes can only be obtained from Delphi machines iirc, a reconditioned injector should have a sticker put on it with the new codes written on it, anything else will be a waste of money.