If you have
- The manual
- Tried all of the codes
- Tried a search
and you've not found a code, the likelihood is there isn't one.
However, I've collected together a swathe of code lists and manuals; all of which can be found hereNotes:
- The manuals in the Chinese section are in, err, Chinese; apparently a fact not obvious to some.
- There are at least two models (RM-101 and RM-969E) that have variations using using both 3 and 4 digit codes.
- The very latest models are using 5 digit codes that I've not yet got round to cataloguing.