DEF Usage

Q:	How much DEF will a truck consume?
A:	DEF consumption is expected to be approximately 2 to 3% of fuel consumption, depending on vehicle operation, duty cycle, geography, load ratings, etc.
Q:	What is the number of miles a truck can expect to travel on one gallon of DEF?
A:	DEF consumption is directly related to fuel consumption. A truck averaging 6 MPG can expect to go approximately 300 miles on one gallon of DEF.
Q:	Is any maintenance required on the DEF Dosing Unit Filter?
A:	The DEF Dosing Unit Filter will need to be replaced about every 200k miles as part of routine maintenance.
Q:	How can an operator determine how much DEF they will need/use?
A:	The average consumption rate of DEF is between 2-3% of the diesel fuel consumption. For example, for every 100 gallons of diesel fuel consumed, between 2 and 3 gallons of Diesel Exhaust Fluid will be automatically injected into the exhaust system. A typical diesel truck should go about 300 miles on one gallon of Diesel Exhaust Fluid. The refueling interval will depend on the size of tank you have. If you know the average fuel consumption of a vehicle, and the DEF dosage rate, you can easily calculate the estimated amount of DEF that will be used. For a quick calculation, go to DEF Usage Calculator Here is an example at 2% dosage rate: Annual miles for average truck = 120,000 miles MPG for average truck = 6 mpg 120,000 / 6 mpg = 20,000 gallons diesel fuel per year DEF usage @ 2% of fuel consumption = 400 gallons of DEF / year 400 gallons / 20 gallon tank (average size) = 20 DEF fill-ups / year Here is an example at 3% dosage rate: Annual miles for average truck = 120,000 miles MPG for average truck = 6 mpg 120,000 / 6 mpg = 20,000 gallons diesel fuel per year DEF usage @ 2% of fuel consumption = 600 gallons of DEF / year 600 gallons / 20 gallon tank (average size) = 30 DEF fill-ups / year
Q:	Is the DEF dose rate the same for all engine manufacturers?
A:	The DEF dose rate will vary slightly amongst engine manufacturers. While most engines will have a dose rate of 2% to 3% of diesel fuel consumed, the dose rate will range from 1% to 3%.
Q:	What happens if the vehicle runs out of DEF?
A:	Vehicles using DEF will have indicators on the dash that will alert the driver of the DEF quantity on board. A gauge similar to a fuel gauge will indicate the DEF level. There will be a DEF low level warning lamp illuminated when DEF is low. If a vehicle is operated to the degree of running out of DEF, vehicle power will be reduced enough to encourage the operator to refill the DEF tank. Once the tank has been refilled the engine will resume normal power levels.