D.E.F. CONSUMPTION AND POOR GAUGE PERFORMANCE.

tgivanoff · July 15, 2021

I have notice on my 2021 silverado 3.0 duramax that the def consumption really increases with trailering. I have hauled a 7000# travel trailer 2000 miles and experienced consumption at a rate of around 2.5 gallons per 400 miles travel. My mileage while hauling is at 12.5mpg. This is half of my usual mpg as when i am not pulling a trailer i average 24 to 29 mpg. A month before i traveled 3000 miles not hauling and went through less than 3 gallons of def. The other problem i have found is that i get warnings of 779 miles remaining before i run out of def but the def green gauge shows full. Any idea if i have a problem with these issues? Any recall notices?

David Krueger · August 24, 2022

I just bought a 2021 AT4. It replaced a 2017 Colorado with a 2.8 L TD. So the Colorado didn't have any kind of guage on the DEF tank. It was truely a guessing game. If you let the tank get low, the check engine light would come on. What a pain in the ass! So I was excited that my new truck had a guage. From past expierience, Yes you will deffinetly use more DEF when towing.

So far I am seeing that the guage isn't very accurate but simply a guide. I filled the tank when I got it and I have the trip odometer set to see about how many miles that I can get on a tank of DEF. Just a starting point. I also get a message saying how many miles left on DEF.

I recently towed my boat on a 3,000 mile trip and got 18 mpg average for the whole trip. I have noticed that the mpg is matched to the mph. At 60-65 mph I would get around 20 mpg, and at 70-75 mph I got 17 mpg.