My Qashqai Tekna has a really irritating buzzing noise which only happens when the car is started from cold (eg after being left overnight) and lasts about 3 - 5 minutes before disappearing for the rest of the day!
It sounds like its coming from the footwell behind the lower dashboard and reverberates mostly when revs are applied as car is pulling away.
It seems to me that it must be something which expands when it warms up which is either not properly secured or which is positioned next to something which does that.
Any suggestions please? My local Nissan dealer can't find it although I accept it's hard to track down because it only happens for a few minutes each day!