Symptoms

DEF, DPF and regeneration warnings

What causes it depends on the engine. 27 documented failures on 14 engines list this among their signs. Pick your engine for the causes ranked, how to tell them apart and the usual fix.

6.4 Power Stroke (2008-2010) 1 known cause: DPF clogging / regeneration problems 6.7 Power Stroke (2011-present) 2 known causes, most widespread: DEF / SCR / NOx sensor faults 3.0 Power Stroke (2018-2021) 2 known causes, most widespread: DEF heater faults and harness corrosion (P20BA) 6.7 Cummins 2007-2018 4 known causes, most widespread: DPF clogging / regeneration problems 6.7 Cummins 2019+ 2 known causes, most widespread: DPF/SCR aftertreatment problems (2019+ 6.7) Ram 1500 EcoDiesel (2014-2019) 1 known cause: DEF tank / heater faults (frozen-DEF derate cycle) Duramax LB7-LMM (2001-2010) 1 known cause: LMM DPF-era service (regeneration / ash service) Duramax LML (2011-2016) 3 known causes, most widespread: DEF system failures: tank heater, dosing, quality (LML) Duramax L5P (2017-present) 3 known causes, most widespread: DEF system failures: tank heater, dosing, quality (L5P) Duramax 3.0 (LM2/LZ0) 4 known causes, most widespread: DEF system faults: tank heater, pump/quality (speed-limited derate) 3.2 Power Stroke (Transit) 1 known cause: DPF / DEF-SCR aftertreatment messages and service ('Drive To Clean') ProMaster EcoDiesel (2014-2016) 1 known cause: DEF/SCR and DPF regen duty (2014-2016) Sprinter 3.0 V6 (OM642) 1 known cause: BlueTEC DEF/SCR: sensors, DEF quality, countdown derate (2010+) Sprinter 2.1 (OM651) 1 known cause: BlueTEC DEF/SCR service (2014-2018)

Built from the failure-mode records on this site: a failure is listed when its own symptom list describes this sign. Engines not shown have no documented failure with it in our records. How we tier and source facts.