Mine was always about 5'C warmer than actual & that of my friends R3 - bugged the hell out of me.
The ambient temp sensor is a stand alone one (i.e. separate to that used by the engine management) and is located under the front cover with a rubber tube routed down behind the LHS fork. The tube terminates on top of the bottom triple clamp.
My tube was slightly kinked - after freeing it up, it now reads more accurately and is within 0.5'C of my friends.
Re. being slow to respond to temp changes. My guess is that this is due to the tube being quite long and sealed at the sensor end (it just slides over it) so there's very little movement of air through the tube. I intend to cut a small hole in the side of the tube just below where it fits over the sensor; the idea being that this will allow air to flow over the sensor & give more rapid temp updates assuming reading intervals are not too slow due to software settings.
