DD15 Water on the Delta-P sensor

First off, I'm an O/O and not a mechanic, but desperately need advice.
I am constantly getting MILs, CILs, derates and the occasional loss of throttle response and when I pull the Delta-P sensor off the venturi I am finding little films of water across the port on the EGR side. It's not coolant or oil but water. The ports are clear. Seems to have culminated with the frigid temperatures but even in areas where its just above freezing, it persists. I haven't been anywhere hot since it started. Errors I'm getting include, but are not limited to:
SPN 2631 FMI 1 Smoke Mode
SPN 411 FMI 13
SPN 2659 FMI 0 EGR Target flow
SPN 411 FMI 2
SPN 3058 FMI 10 MIL and occasional CIL. The CIL will derate but will go out on its own. I did replace the Delta-P with no change.
In every occasion, I open it up and there's water. Just a tiny bit. Enough to cover the port from the EGR side.
What's causing this, please?

Thanks

 

I should mention, I did run mechanics wire through the ports on the venturii and they have no blockage. I don't idle overnight. If it's very cold I'll run it intermittently. I had the One-Box replaced over the summer. Is a possible exhaust leak the culprit? Sometimes i hear squealing at the engagement if the Jake brake