ECM sensor ?

Hi every one done a search but can't find anything on this. Whilst playing with my engine today (TD4) decided to remove the cover that hides the ECM and noticed a sensor under the cover next to the ECM it has two wires going to it but the sensor just pushes into a plastic hole and doesn't seem to have anything below it, any one know what this is and what it does.
Cheers Michael

It's an ECU environment sensor. Basically it switches on a small fan inside the ECU box. This is to limit the maximum temperature of the air around the ECU.
You will find 2 rubber hoses at the rear of the ECU box. These take air to an from the scuttle.

Oh I see cheers for that, that does make sence.