[dualfuel]

This does sound like a decoder problem, but have you tried a factory reset on the select and then try reprogramming the decoder?

Only reason I suggest doing that is the problem appears to have occurred after you split the consist - which is a select function not the decoder.

I had to carry out a factory reset on my select after trying to program one of my NCE decoders, which didn't program and then left the select in a weird state where it would go through the motions but would not actually control anything.

I have not come across the problem of decoders returning to address '03' after consist handling..... yet!

 

[dualfuel]

I had a hornby decoder go back to '03' today also. I think what happened is I had a momentary short circuit with a derailed train throgh some points, and one loco on the system (class 47 - coded as '47') when I next tried to use it wouldn't move. I then guessed maybe it had gone back to '03' tried it and yes it had.

The only other loco on the 'live' track was my NCE decoder fitted battle of britain, which was already coded as '03'.

I think either the Select rebooted after the short and reprogrammed everything to be '03' (so in this case only the 47 changed numbers), or it is a problem caused by having the NCE decoder on the track when a short circuit occured.

I will try to experiment further to see if I can get it to happen again!