Yeah it is brand new, only had it for about 3 days!
I have had a look, i don't think i am going to be able to find out for sure until i give it a proper fly outside. I did a recording test on my iPhone and i can hear very clearly the Ultra Sonic working, but for the time being i am going to wait until i have had my first proper outside flight before contacting DJI... Which i have heard isn't the best.
I bought the drone from a company who appeared to be in the UK, they are actually based in the US so i am worried that i may have a US warranty (which may mean it will need to be sent back there for repair?).
Yeah let's hope it's nothing, personally I'd be reluctant to fly it with any errors. What firmware is it running? have you tried a firware update?