Failure mode - Ram 1500 EcoDiesel 3.0L V6 (2014-2019)
DEF tank / heater faults (frozen-DEF derate cycle)
Reliability tier: verified - verify before ordering, see /disclosure/
Symptoms
- 'SERVICE DEF SYSTEM - ENGINE WILL NOT RESTART IN 200 MI' warnings, DEF gauge stuck (commonly ~1/4), P20EE/P20E8 codes
- cold-weather faults from an inoperative tank heater; repeated tank-unit failures reported (2-3 replacements), often out of warranty
Compare with the other causes of the same sign on this engine: def, dpf and regeneration warnings
Root cause
The 2014-2016 DEF tank unit (heater element + level/quality hardware) fails and forces the escalating derate-warning cycle. VOQ cluster: 40 of 1,785 VIN-confirmed complaints concentrated in 2014-2016 (2014:13, 2015:13). Community consensus (ram1500diesel forum + repair shops): the tank-side unit is the weak link; FCA handled it with service actions rather than a safety recall.
Diagnosis
- read the DEF codes before replacing the tank - NOx-sensor and doser faults mimic the warnings
- cold-weather-only faults = heater circuit; year-round gauge faults = level/quality hardware
Fixes
replace the DEF tank assembly (heater + level/quality hardware ride on the tank unit) ()
- def-tank-assembly - more than one option: Ram 1500 EcoDiesel DEF Tank Assembly with Temp Sensor (Mopar 68161432AI, 2015), Ram 1500 EcoDiesel DEF Tank Assembly with Temp Sensor (Mopar 52029737AI, 2017-2019)
replace the DEF pump/dosing components when tank-side pressure or dosing codes appear ()
Prevalence
common
Parts for this repair run about $230-$2,350: see them next to the other repairs on this engine in repair costs.