What is this pipe?

[Allandwf]

Hi, what is the small black pipe that , i think , should be connected to the rear of the nearside air intake box on a 4.2. It comes through from the passenger bulkhead. It's disconnected on mine.

[Tanguero]

ECU barometric pressure sensor. Yes - it should plug into the back of the airbox.

[Allandwf]

Thanks, will plug it in after replacing the small water pipe below it thats US.