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

An adequate on-board supply of Diesel Exhaust Fluid (DEF) is critical for the reduction of exhaust Oxides of Nitrogen (NOx) levels within the Selective Catalyst Reduction (SCR) stage. This vehicle provides the driver with an elaborate series of prompts and warnings that are initiated when the DEF level falls below a calibrated value.

The Engine Control Module (ECM) monitors the DEF level and consumption rate in order to calculate an estimated range in miles remaining until the DEF reservoir is empty. DEF levels are detected by the DEF level sensor. Typically, DEF warnings begin once the estimated mileage falls below 1, 609 km (1, 000 mi). Once initiated, DEF warnings grow increasingly more serious as the remaining mileage decreases without a DEF refill. The vehicle's current DEF warning level is displayed on the scan tool as Reductant Level Warning Indicator Command Level 1 through Level 14.

The scan tool Reductant Level and Reductant Level Sensor parameters should change when DEF is added to the reservoir. If the parameters do not change, the reductant level sensor may be stuck.