what is this hose - leaking coolant
 

vehicle is a 2009 mazda5. 3 months ago, the coolant flange was bad and the mech replaced it, coolant was refilled. Today I checked again and coolant is low and had to add almost a gallon but the leak is from somewhere else. It's from this hose below the air mass intake on the driver side. see pic, it's the reddish thing in the middle of the pic, anyone what that is , is it pretty easy to diy?

edit: enhanced photo.

thx


https://cimg3.ibsrv.net/gimg/www.maz...f2fd42313.jpeg