I drive a Audi A4, 2005 model and for the past few days the temp gauge measuring the outside temperature has been going mad.

One minute it is 15 outside, the next I notice the temperature droping 0.5 every couple of seconds until it hits minus figures. Yesterday I achieved -23.

The next thing I see is it increasing by 0.5 until it hits the correct temperature. A few minutes later it's back in the minus figures.

Any suggestions what could be happening, has anyone experienced this before?

Could this be a warning sign of a fault?

Cheers
Richard