excessive DEF useage

[RichardJ]

I have a 2020 silverado 1500 with an L6 diesel. I recently used 5.8 gal def on 1006 miles trip (10 - 12 mpg). The previous 1400 miles used .5 gal 25 mpg

 

[zora]

Since it is a brand new truck, is there a reason you dont take it back to the dealer for service?

 

[RichardJ]

Since it is a brand new truck, is there a reason you dont take it back to the dealer for service?

I did they said it is working fine because the diagnostics showed no errors. Just wanted to see if others are having same problem