CV08 is the factory reset CV for all FX3 decoders and also the Manufacturer ID CV for all decoders.
When you read the value of CV08, Digitrax decoders report back "129".
To reset all CV values to their factory default, program CV08 to a value of 008/x08 while the locomotive is on the programming track.
To reset all CV values except for 28 step speed tables to their factory values set CV08 to a value of 009/x09.
Note: Performing a factory reset will not affect the manufacturer ID and will reset the decoder's address to the factory default of 03, a 2 digit address.