DD13 code Spn 6259 fmi 0, anyone have experience with this?

I realize this is an old thread but anyone with similar

The crossover pipe IS the pipe the Delta-P sensor is mounted upon. There are two ports beneath the sensor. As they loop around they are nearly impossible to clean. I have 3 of them kicking around the house.

The moisture could be condensation accumulating because of plugged ports.
However, if your coolant is disappearing it is imperative to determine if your EGR Cooler is leaking. If it is and its dumping coolant into the One-Box it will quickly corrode the precious metals in the One-Box. One that happens you're forced to the 5mph derate. They're $10,000-14,000 just for the part.

 

Pipe cleaners work best.

For anyone too young to remember, you get them at a tobacco shop.

 

I've never been able to get a pipe cleaner through one with a blockage. Once the Carbon starts packing in. Mechanics wire. The kind you'd tie up a tail pipe on a car forced with a pair of electricians pliers. I knew a mechanic once who would use that method while heating it up with a torch.