I always recieve some good info here so i need help again. I'm working on a "09" Mack CXU613 (MP7) A few months ago we replaced all 6 injectors and not long after that we had to replace 2 due to fuel leaking from the bodies. All was working fine but came back with mid 128/psid 47/ fmi 0 and soot level codes. Checked regen system,found tee check valve at A/T fuel inj faulty. Replaced the check valve and all was good again. Returned again with same codes. Tried running regen and would not build temp. Removed dpf and sent to be cleaned. Reaseambled and ran regen. Still not temp. Have fault traced with G/D. Replaced egr valve. checked diff sensor,tubes,vgt lever,boost leaks,fuel pressure to A/T fuel doser and made sure it wasn't plugged. During regen the exh temps are (inlet 739) (after cat 969-978) (outlet 877-904) It goes back to idle and soot level reads the same and only code active is for soot level. I'm heading towards faulty DOC but who want to spend 5k on a guess? Any ideas?