Touching the removed battery cables will ground any stored electricity in the computers and remove all faults - everywhere. But, you will need a long drive cycle to get the computers to learn your driving habits.

This works for MAF learning as well as auto tranny learning. The engine will 're-time' itself. This is a good thing, not something that should never be done. Just remember, these modern cars all have components that communicate with each other, and your car must re-learn to achieve what it thinks are optimum conditions to your region and driving style.

Your O2 sensor does store readings in the computer, but a couple of drive cycles will replace the old readings. Example, my wife drives an Audi A4 which turned on a CEL due to the rear O2 sensor reaching the high limit. I fixed the cracked flex pipe in front of the Cat and after 2 days, the CEL went out by itself.

Klaus
--
There is no present time, just the past and future