Good call !I think I heard someone say that DEF is pumped out of the line back to the reservoir at shut off to prevent freezing. Could that be a small pump dedicated to that action making the noise?
Based on all the posts above - it's a DEF pump retuning fluid to prevent freeze-up. Sounds like many have it. I do not - but perhaps it's because I do not do too many short drives.Mine makes the noise as well consistently. Is repair needed ? Is this signs of impending failure? My truck only has 20k on the clock