Failure mode - Cummins 6.7L ISB Diesel (Ram HD)

DPF clogging / regeneration problems

Reliability tier: verified - verify before ordering, see /disclosure/

Symptoms

'exhaust filter full / regeneration required' message on the overhead console
frequent or endless regenerations; aborted regens on short trips
loss of power (inducement / derate) until regeneration completes
excessive idle, white/grey smoke during regen, hot exhaust smell
fuel smell in the oil after repeated failed regens

Compare with the other causes of the same sign on this engine: loss of power, limp mode or derate (6 causes) · white smoke from the exhaust (3 causes) · def, dpf and regeneration warnings (4 causes)

Root cause

The diesel particulate filter loads with soot faster than active regenerations can burn it off when duty cycles are city/short-trip or idle-heavy. 2007.5-2012 trucks (DPF-only, no SCR) regenerate most often; 2013+ SCR trucks run fewer, cooler regens. A stuck VGT (used to drive exhaust-brake regen heat), inoperative EGR or sensors, and failed regens compound into an overloaded filter.

Diagnosis

read DTCs (P242F/P2463 soot-load, P204F etc.) and soot-load / ash-load PIDs before replacing anything
verify regen completes when driven at highway load (30+ min); a filter that regens clean is a duty-cycle problem, not a part problem
differential-pressure check across the DPF; inspect for cracked/missing substrate
rule out stuck VGT and EGR faults that prevent reaching regen conditions

Fixes

restore duty cycle: sustained highway load so regens complete; correct the underlying reason regens fail (VGT, sensors, EGR) before replacing the filter ()

vgt-turbo - more than one option: Holset HE351VE VGT Turbo (2007.5-2012 pickup), Holset HE351VE VGT Turbo - Mopar Reman (2007.5-2012 pickup, current PN R8048234AI), Holset HE300VG VGT Turbo (2013-2018 pickup)
6.7 Cummins EGR Valve

professional DPF cleaning (bake/pulse) when ash-loaded but substrate intact (clean the filter) - cheapest path that keeps the truck emissions-compliant; only works if the substrate is intact

cummins-6_7: dpf-cleaning-service (service item)

replacement DPF (OEM replacement) - keeps the truck fully legal; the expensive path

6.7 Cummins DPF Assembly

Prevalence

very-common