i had this problem with my old motor, it would put the light on every time the weather got hot, or veyr cold,,,
the car still drove fine tho, and nothing ever missed or coughfed or splutterd once, i got a scanner/ diognostic tool and ran a test, it said mass air flow meter, i put a new 1 on £58 of ebay, got rid of the code and put the light out, 2 weeks later blink,, its on againe but the weather had got a bit colder. ran the test maf meter again,,,,,
put light out, blink, up ti popd again with a new code, cam shaft sencer bank 1 reeding fault???? then it was running too lean??? never got to the bottom of it, nor did audi, but the madist thing of all, when the weather got better the light went out,,,,all by its self....