Road Numbers

I don't see these US prefixes, I see the correct numbers, both AU and Europe. They would come from the map anyway which is derived from OpenStreetMap ( https://www.openstreetmap.org ), check out the location on OSM and see what the number is there. OSM is created by a community, anyone can register and edit the maps, it is possible the creator of the map elements gave a wrong number. Can you do a screen shot or share the location, is it only in the 1040 Guide Text at the top of the map or in the map itself?

The road numbers on the map itself are fine. No "US" prefix there. It's the on-screen instructions to your destination at the top of the map where I see US+RoadNumber displayed. 1040 APAC model set to English language.

If you tap the Guide Text at the top of the map you will get the Turn List, full list of the calculated turns, what do you see there? Are the turns related to your loaded / calculated route. 

Below are some examples off the Turn List. Switching the language to Japanese is all fine no US prefix being added. Just the kanji for road + the actual road number. Some roads have name others just the number.

You have reached the limit of my suggestions, you will have to get more from a local or Garmin support Japan? I can only think it is an error in the translation files, the kanji for road/highway has been translated to "US" but in only some situations.

Thanks for your input as always. I will try Garmin Support in Japan seems like this might be some translation files adding the US prefix when the unit is to English.

Can you be specific about the road it's mislabeling?

I'm going to guess that if the name of the road is "101" it's adding the "US" by default.

There's no option to disable it.

It is likely that the map could add a prefix that would prevent the device from adding "US".

It worked for me, thank you for the suggestion.