The 2022 Ram 2500's Cummins 6.7L diesel uses DEF for emissions compliance. When the system detects quality issues, warnings appear and a countdown to speed limiting begins if not addressed.
Cummins DEF System
The system monitors DEF quality through concentration sensors. Proper DEF contains 32.5% urea solution. Deviation from this concentration triggers quality warnings and code P20EE.
Causes of Quality Warnings
Sensor Failure
The quality sensor can fail internally or become fouled with crystals. Failed sensors report incorrect quality readings even with fresh, proper DEF.
Contaminated DEF
DEF contaminated with diesel fuel, water, coolant, or other substances triggers warnings. Even small contamination amounts cause problems.
Diluted or Degraded DEF
Old DEF or DEF stored improperly can degrade. Water evaporation changes concentration, triggering quality faults.
Crystallization
DEF crystals forming in the tank or around sensors affect readings. Crystals form when DEF is exposed to air or temperature extremes.
Speed Limiting Countdown
Ram's system provides warnings before limiting speed. First you receive messages, then torque limiting, and eventually 5 MPH maximum speed until repairs are completed.