It’s the gearbox temp sensor.

 

from memory, it's down low on the front of the passenger side of the radiator.

 

Yep. Lay on your back under the bumper and look up

 

Ended up mounting essentially where I was holding it in the pick. Maybe it's in a different spot for a 2002 compared to your Disco? I think in 2003 they changed something about the oil coolers since there's a section up to and after 2003 in the RAVE.