Insite Help exhaust (SCR/DEF) service required

[jimeneztrans84]

You should remove the scr can too and look inside for crystallized def. This should be done maybe once a yr to inspect for any crystallized def.

[snailexpress]

I'll bet the DEF filter was never changed. Check it first before replacing expensive parts.

[feltup]

having the dpf baked and flow tested is not a bad idea if you have the time. but a mechanical system not responding is the doser not functioning properly. i have seen may of them actually get crystallized and plug up. you can generally clean them with a brass brush and they will work for a bit but i have always had to replace them soon after due to malfunctions. some times doing a pump override test with get the spraying right but its no guarantee. but this was on the early 2250 engines when they first came out.

[Longshot]

Thanks all who provided recommendations on how to tackle this Exhaust SRC DEF issue.
Here is an update:
We dropped the drive shaft to get access to the DEF Doser Valve / Injector.
The 3 - 6mm bolts that hold the doser valve to the Decomposition Reactor all broke off even after applying generous amounts of liquid wrench and heat from a torch.
We pulled the Decomposition Reactor tube and drilled, tapped and helicoiled the DEF valve injector mounting plate and reinstalled the Decomposition Reactor.
We then tested the existing doser valve after thoroughly cleaning it - it failed the test and rather than any DEF coming out of the injector, DEF began to leak out of the DEF tubing connection to the valve. We replace the valve, gaskets, bolts and reassembled tubing and drive shaft. We then cleared the codes and went for a test drive and all is well.
But we also know that it is inevitable that another issue will crop up any day.

As most on this site have mentioned having Insite and Inline is an invaluable tool in diagnosing and resolving issues.

Best Wishes and Happy Holidays.

[Waterloo]

Quit screwing around, get down to Georgia and have this issue fixed for good. And don't forget the fuel pump. Mr Haggi will turn your truck into a money making machine, do it now instead of pissing away your money fixing an issue that will bite you in the ass again in a few months. Spend your money wisely, go see Mr Haggi. ;-)