Few problems with my 99-00 S-type

Hi..... I am having small overheating drama when the car is sitting in traffic, it goes from 50% to 75% or higher... but it all happens at once, the meter just jumps a quarter or more. It has never gone over 80%. But i think this is just something i need to take it to the mechanic with..


The other one is a cable hanging down under the car. Between the front tyres. It looks like a data, electrical cable with a plug in the middle of it.


Anyone know what this cable is?


Thanks