The 2020 Ram 2500 diesel triggering P20EE indicates the Selective Catalytic Reduction (SCR) system has detected diesel exhaust fluid (DEF) quality problems. The Cummins diesel in this heavy-duty truck requires proper DEF for emissions compliance.
Understanding P20EE
P20EE sets when the SCR system determines DEF quality is insufficient for proper NOx reduction. This could mean DEF is contaminated, degraded, or diluted. The urea concentration must be approximately 32.5% for proper function.
DEF Quality Requirements
DEF is a urea-water solution used in the SCR system. It must meet ISO 22241 specifications. Contamination, improper storage, temperature exposure, or age can degrade DEF quality.
Causes of Quality Issues
Contaminated DEF from improper handling. Water added to DEF (dilution). DEF exposed to temperature extremes. Old DEF past expiration. Contamination in the DEF tank. Wrong fluid added to DEF tank.
DEF System Components
The system includes DEF tank, supply pump, injector, and quality sensor. The quality sensor can also fail, producing false quality codes. Diagnosis should verify actual DEF quality before replacing DEF.
Ram Diesel Considerations
The Ram 2500 may enter derated mode if P20EE isn't addressed. Engine power is progressively limited to encourage repair. Eventually, the truck may be limited to 5 mph until fixed.
Repair Costs
DEF drain and refill with quality fluid costs $100-250. Quality sensor replacement runs $200-500. DEF pump replacement ranges $400-800. Tank cleaning if contaminated costs $200-400.