2005 E320CDI Post-Water-Pump Code

[Randy]

Hi, just finished changing the water pump, belt, idlers, tensioner, and hoses. Also replaced the manifold pressure sensor (again). When I started the engine for post-repair checks, I found CHECK ENGINE illuminated. Whipped out the trusty OBD II scanner and found 1 code: P0069 manifold absolute pressure barometric pressure correlation.
I erased the code but it resets as soon as the key is on and before the engine starts.
I had to remove the air filter box and turbo inlet elbow duct and unplug the involved harness to change the water pump so I figured one of these is not making contact. I checked and they appear to be fine. Can anyone guide me here?
Water pump and associated repairs seem fine btw.