I think I have just figured out what is going on with code P06DD and I wanted to pass on what I learned. I have seen all sorts of conflicting and seemingly nonsensical info so I hope that others can learn from my experience.
I have a 2016 T&C with about 125K on it. I have the 3.6 VVT engine. A few months ago I started getting the code P06DD and the car would go into limp home mode. My scanner, and posts on several forums recommended a whole bunch of different fixes: Change the oil, Replace the filter housing, and replace the oil pump. I could not see how these oil-related fixes could possibly cause this problem.
I changed the oil, filter, and filter canister. No change. I replaced the filter housing just because a whole bunch of people said this worked for them. This really seemed to make no sense because I could not see that mine was leaking.
This also did not fix my problem. I figured that replacing the oil pump was too big a job until I saw an excellent video on YouTube from the "Motor City Mechanic" that describes a "shortcut" method where you can replace the oil pump while only removing the little, stamped steel section of the oil pan. I decided to try it.
When I opened up the oil pan, I could immediately see the problem. The whole bottom of the engine was covered with thick sludge. Not only that, but the sludge was absolutely baked onto the solenoid that is attached to the oil pump. I cleaned up the sludge as best I could, replaced the pump, and flushed the engine using "Motor Medic Motor Flush" that I got at Walmart. Then I changed the oil and took the car a for test drive. The code finally went away after a couple drives and it has not come back since.
So here is my theory as to what is going on here: I think the oil filter housing is the cause of this problem. I think that it starts to warp and allows coolant into the oil. This then produces huge amounts of sludge which eventually bakes onto the solenoid. Then, when the computer tries to command the oil pump into high pressure mode, the solenoid is no longer able to comply. To me, this explains what is actually happening. Can anyone confirm or deny my theory?

 

More news to report. My code P066D has returned about a week after I installed the new oil pump. However, my scanner shows it as a confirmed, but not permanent code.
I dont see how it could be related, but it appeared along with a code P0463 "Fuel Level Sensor "A" Circuit high".

 

Hi Codosaurus
I have the same problem, What did you end up doing to fix the code P06dd

 

What did you do to fix yours?

 

No update?