Diesel Exhaust Fluid (DEF) Warning Strategy (Diesel Exhaust Fluid (DEF) Quality): Notes

A supply of clean, fresh Diesel Exhaust Fluid (DEF) is critical for optimum Selective Catalyst Reduction (SCR) efficiency. The reductant tank contains a reductant quality sensor that monitors the quality of the reductant (DEF). This vehicle provides the driver with an elaborate series of prompts and warnings that are initiated when the reductant quality sensor detects a diluted or contaminated DEF supply.

When the reductant quality sensor detects contaminated or diluted DEF, the ECM initiates the DEF Quality warning process. Once initiated, DEF quality warnings grow increasingly more serious as the vehicle continues to be driven. The vehicle's current DEF quality warning status is displayed on the scan tool. When a drop in DEF quality is detected, the normally Off Reductant Field Quality Warning Indicator Command will display Warning Level 1 through Warning Level 11 depending on the number of miles driven. The series of DEF Quality Warnings alert the driver that DEF system service is urgently needed. After the condition that caused the reductant quality sensor to detect contaminated or diluted DEF is corrected, the warning message will clear.