You should also read back and write down (I use a spreadsheet) any CVs you commonly change, such as locomotive address and momentum values. Otherwise you'll have to experiment with some of them all over again, because a factory reset will put them back to the way they came out of the box.
It takes an iron man to play with a toy iron horse.
You need to know what decoder it is. Different brands use different reset options, but the most common are CV8=8 or CV30=2. Both are read only CVs but will make the reset happen - if you read them back they will still show the previous value, CV8 being the manufacturer ID assigned by the NMRA.
Older decoders usually did not have a single CV reset option.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
What information would I need in order to reser a decoder to its factory settings? I use an MRC Prodigy Advance 2 and the decoder is an older decoder in an Atlas loco.