A P20EE code in your 2018 Ram 1500 EcoDiesel indicates the Selective Catalytic Reduction (SCR) system isn't achieving required efficiency levels. This emissions system uses Diesel Exhaust Fluid (DEF) to reduce NOx emissions, and P20EE signals problems with the process.
Understanding the SCR System
The SCR system injects DEF (urea solution) into the exhaust stream where it reacts with NOx in the catalyst, converting it to harmless nitrogen and water. The system monitors this conversion efficiency through sensors before and after the catalyst.
P20EE Significance
P20EE indicates SCR catalyst efficiency below threshold. The ECM monitors NOx levels and when conversion falls below expected levels, this code triggers. If not addressed, the vehicle may eventually enter reduced power mode.
Common Causes
DEF quality issues from contamination or dilution affect reaction chemistry. DEF injector failure prevents proper fluid delivery. SCR catalyst degradation from age or contamination reduces conversion capability. NOx sensors providing incorrect readings trigger false efficiency codes.
EcoDiesel Specific Considerations
The 3.0L EcoDiesel's emissions system has been subject to recalls and updates. Verify all applicable recalls have been performed, as some address SCR system calibration and components.