Volvo VNL W D13 P20EE00 DEF ISSUE

It will. Address it before it addresses you.

 

Here is a thread. Note #28, the first one in Feb. Also #22. Volvo d13 often parked regen and quick soot level increase | Page 2 | TruckersReport.com Trucking Forum | #1 CDL Truck Driver Message Board
I doubt you have a flow problem. If you did it would be asking for regens or derating. What does the percentage for the DPF read on the dash?

Read the posts in this thread, especially #8.
Ash accumulator reset. SPN247. Which portable reader.... | TruckersReport.com Trucking Forum | #1 CDL Truck Driver Message Board

Without the software and diagnostics/data it is a guessing game which can get expensive fast. Look closely for any black soot which would indicate a leak.

 

Another thread. Start at the top. When you get to the Oct 1, 2016 thread there is a link to a TTR thread.
DEF crystallizing at the DPF outlet elbow/flange - Engine and Transmission - BigMackTrucks.com

 

A lot going on in those threads. Here is what I would do for the fastest and least expensive way to find the problem(s).
1 - After reading the Mack thread I strongly believe you have a leak(s). By far the best way is to find someone to do a pressure/smoke test where the system is pressurized to about 20psi and see where the smoke, if any, comes out. That should not cost a fortune, maybe a few hundred at the most. Did you use new gaskets for the flex pipe and doser? One O/O on here had an Int'l that was in the shop for about a month with the NOx efficiency code. He said changing the doser gasket solved the problem as there were 2 gaskets and the shop used the wrong one. While it was a while ago another O/O told how Volvo had defective flex pipes with holes in them.
2 - If #1 does not find any leaks I would get a software update for the ECM etc.

 

Did you look up into the SCR when you had the pipe off?

Eventually you gotta quit looking outside and see what it looks like inside.

Just take the DPF apart and see what you got. It probably needs cleaned anyways.

When I say flow issue, you have something keeping your exhaust from moving. Leaks, blockages, etc.

You can sit here and play 100 questions or just go find out WTF is wrong.

 

Don't forget to look into the SCR. It is likely part of your issue.

And you can buy all of the gaskets and clamps aftermarket for 1/4 the price of Volvo