Mk 3 Ambient Air Temp Giving Inaccurate High Reading

[Bluetractorman]

My 2008 galaxy reckons it's 38 degrees today in west sussex, it's not.  More like 16.

Also the air in the car was too cool and need to set the internal temp to 23 to feel comfortable.

Is this simply the outside air temp sensor failing?

If it is, where is it located and will switching it for a replacement be a straightforward job?

Can it be tested?

Very grateful for any advice.

Richard