High exhaust back pressure

[JimT]

(06-26-2020 )Rawze Wrote:  check the decomp tube while you are at it...
http://rawze.com/forums/showthread.php?t...07#pid1807

use a boroscope and check the face of the SCR element to see if it is face-plugged too.

^^^^^^^^^^^ Do this! ^^^^^^^^^^

(07-08-2020 )DannyA Wrote:  Any idea on what can cause this high exhaust pressure? Is possible to have a failed SCR and is blocking the exhaust? If the SCR is bad will not show up as some kind of NOX codes?
Anyone have an ideea?

NOx related codes are just that, NOx related. In your case something is causing an exhaust restriction. Or you have a bad sensor. Start by checking the decomp tube for a cone of DEF buildup. Then move on to the SCR can. Internally it looks just like a DPF and if particulate (including dried up DEF) works it's way in there it can clog up. Try disconnecting the exhaust pipes in different places to see if that changes the pressure readings. Start at the SCR can and work your way back until you find the source.