Install Outside Temperature Gauge (A6 C4 '97)

hello boys,
Since it's slowly getting colder again, I was thinking about possibly installing an external temperature display.
I have to say that, unfortunately, there's nothing installed behind my combination instrument for that display yet.
If I understand correctly, both the display itself and the temperature sensor would need to be retrofitted.

What do I need for this, and how much effort is involved?
You can occasionally find the display and sensor on eBay.

Thank you for the tips and the help.

greeting inside

Hi,
"I once had to remove the instrument cluster from my A6 because the outside temperature display wasn't working, and as far as I remember, the connections were directly attached to the cluster."
The sensor is located at the front, underneath the bumper; the cable should already be routed there.

Check it out under.
http://www.audiquattro.de/infos/ata/index.htm
Here's a description of the lighting repair; you might be able to understand something from the photos.

Regards,
Olli.

Could you or someone else help me with this? If the cable is already installed, does it just hang loose? Please describe it as accurately as possible.

Thank you for your help.

greets inside