As David says calculating the new codes isn't a necessarily a problem however applying them could be.
Can assure you that a certain part of your anatomy gets some overtime as mine did today recoding that V8
, fortunately all went well.
After all the mucking about and trying different things to various cars over the last few weeks I can confirm that the electrical systems are fairly robust and hold up quite well, also the T4 (Testbook version 4.Computer Diagnostic System)
is pretty stable when presented with things it doesn't expect.
I think the main danger would be a car that is diagnostically unstable, I think trying to re-code a car with an intermittant communication problem could cause it to not apply the codes correctly.
I suppose a note of the original code and checksum is a good idea so that if need be it could be re-applied.