Passat TDI 2013 rattle under car after engine shut off.

I have a VW Passat TDI that sometimes has a rattle in the under carriage after turning the car off. I noticed the car has to be warm, and it lasts for a minute. I have a video, but don't see a way to attach it here. I am wondering if it is the fuel pump, because I don't see anything else electrical under there. It can't be a loose heat shield, because the car is off. Any other ideas

You have to post it to youtube for instance and then post the link to it here.

Here is the link to the video...
https://youtu.be/TJPqFp4O5l0

That is with the car not running? You said after you turned it off.

Sounds like it is in a regen and the fan blades are hitting something off and on.

Yes, it is with the car off. The fan is still running on the engine, but only for a minute or two. I will check on the Regen and let you know