Hi @markosesquer ,
Here’s the [https://cardiagn.com/jaguar-x-type-sedan-estate-wagon-workshop-manual/|Jaguar X-TYPE Sedan/Estate Workshop Manual] that covers your model.
Scroll down and click on ''Powertrain > Engine.'' In this section of the manual, it mentions two heated oxygen sensors for the engine and shows their locations etc.
I don’t know what the difference is between the sensor connector colours but it may possibly have to do with the specifications of the sensor and their location.
Hopefully this is of some help.