DEF Mileage
4-25-2015. For anyone who is interested - I just posted an update on page 3 with my latest mpg after just refilling the DEF tank yesterday. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++...
Forum Discussion
I monitor my DEF consumption very carefully as my 2011 GM Duramax did not come with a DEF tank gauge and it has caused me some grief on trips. As mentioned the DEF consumption is a percentage of the amount of fuel burned and so it varies depending upon how hard the truck is driven and the load it carries or tows.
My DEF consumption with a bulky 4,000 lb. load in the bed that creates a great deal of air drag is approximately 750 miles per gallon. With no load and driving at 65-72 MPH the DEF consumption is averages around 1000 miles per gallon. I would not be at all surprised that a newer truck get more miles per gallon of DEF. As the truck manufacturers gain experience with the systems they are going to be able to improve their efficiency as with everything else.
I had a period where my DEF consumption skyrocketed and after a lot of effort and visits to three GM dealers it was diagnosed as a failing NOx sensor. As the NOx readings were in error the engine computer was sending more and more DEF into the exhaust to compensate. Others get bad DEF quality or similar error messages and most likely the problem is also related to one of the NOx sensors.
My DEF consumption with a bulky 4,000 lb. load in the bed that creates a great deal of air drag is approximately 750 miles per gallon. With no load and driving at 65-72 MPH the DEF consumption is averages around 1000 miles per gallon. I would not be at all surprised that a newer truck get more miles per gallon of DEF. As the truck manufacturers gain experience with the systems they are going to be able to improve their efficiency as with everything else.
I had a period where my DEF consumption skyrocketed and after a lot of effort and visits to three GM dealers it was diagnosed as a failing NOx sensor. As the NOx readings were in error the engine computer was sending more and more DEF into the exhaust to compensate. Others get bad DEF quality or similar error messages and most likely the problem is also related to one of the NOx sensors.
