Just recently my car is showing around 5 degrees celsius higher than normal.

When I first start up the outside ambient temperature starts a bit lower than actual then as I drive it increases higher and higher to about 5 degrees celsius above the actual.

No indications are showing on the but It feels like my air conditioning system is acting strange to what temperature I set it at.

I am waiting for a nice day to give it a car wash thinking that the sensor might be dirty and it just rained yesterday. In the rain, the indicated outside ambient temperature was fairly close to actual if not actual (based on my weather app on my phone).

Where is the sensor located on my 2012 Jaguar XF, is it the passenger side mirror? Can I access or clean the sensor without disassembly?

I am taking the car to the mechanic for my annual service and could have the opportunity to get the mechanic to replace if needed unless I can do it myself and save some cash.

 

On RHD models the temp sensor is on the underneath of the passenger (LHS) exterior mirror, not so sure about LHD models though.
Have a look under both your exterior mirrors and you should be able to spot it.
I don't know how easy or difficult it is to access and clean the sensor.