Whine after shut down?

[Grizzly16]

When I shut down and get out of the truck, I hear a slight whine (motor humm) for about 20 seconds from under the hood. Anybody know what that is? (Its done that since day one, so no issues, etc....just wondering). Thanks for any response!

[kschmidt64]

The urea system is supposed to suck all the fluid back into the tank when you turn the truck off. This way if it freezes, the tank heaters can thaw it back out. I assume what you're hearing is the sound of the pump running to draw the urea back in.

[mcflan]

Turbo? haha

[Grizzly16]

Urea system seems to make sense. Thanks!

[atvrider93]

your turbo slowing down.....

[Grizzly16]

No, it's not the turbo. This is an electric pump making a slight humm for a specified amount of time followed by distinct shut off.