This is very common problem. I had this exact issue for 2 years before I figured out exactly what it was. Limp mode on long 1-2 hour highway drives (Chicago) and locked out of lower gears/ratios. The factory overfilled my CVT fluid causing oil foaming and insufficient cooling/lubrication which caused belt slippage. Yes, the CVT run hot and those in hotter climates or mountain regions would most benefit from an external cooler. But if the CVT oil level is set correctly and the fluid and internal filter cartridge is changed regularly this will most times cure the overheat/limp mode issue. I highly recommend AMSOIL synthetic CVT oil as it eliminates belt slippage and clutch shudder and seems the CVT ran cooler but that also could have been the filter change as well. This solved my limp mode problem completely and it never recurred. I never needed to upgrade to an external cooler as the difference was night and day but I hear many owners swear by a cooler upgrade and I would recommend it as well.Hi I actually have experienced this several times with my 2013 juke during long drives in the summer. It's an engineering flaw that I simply can't believe made it through approval. The cvt overheats and so the juke limits rpms and (dangerously) cuts power. I spent good money getting the cvt it's own radiator to help keep it cool and it helped but didn't solve the issue. Now on long trips I have to tell waze to take backroads to keep my speed and heat down - the engineers at nissan should be embarrassed that every single other car on the road does NOT have this issue. I'm currently on a trip where it happened again and will change my transmission fluid just to make it home. Such a joke.
Not saying the engineers aren't at fault but a factory worker overfilled my CVT oil and majorly screwed up my transmission until I corrected the issue although damage was certainly done.