2020 Silverado 2500 DEF usage

CO 2020 GMC AT4 · June 26, 2020

I'm experiencing the same issue, especially when pulling a good load. Hauling hay in western CO, empty flatbed gooseneck weighing about 5k, then loaded with 14k of hay back up hill to the house. 7 trips, 882 miles, half without hay, burned over 5 gallons of DEF.

Truck handled the load nicely, really like the 10 speed, topped out on a 1 mile 7'% grade at 48 MPH. GVW around 27k....Not bad starting at 45 to make the curve at the bottom....

gjohnston7 · June 27, 2020

Thanks CO 2020. I guess I should be happy with my 300 miles per gallon. Hopefully GM will figure out what is going on. I asked my dealer for the grater test that was mentioned earlier. Crickets.

Alan Juden · June 28, 2020

@gjohnston7, that's my fault...I called it the "cheese grater test" but it's actually the "cheese cloth test". They said that they had to put a cheese cloth over something to check the amount of particulates coming through the exhaust. I found a similar article about it: https://static.nhtsa.gov/odi/tsbs/2019/MC-10161931-9999.pdf

Sorry for the confusion on the name of the test.

cNate · July 1, 2020

I posted a thread on this a few weeks back. I’m getting 300-400 per gallon towing 9k lbs trailer. My sensor misreads all the time. Just filled up and it shows half empty still. About 500 miles into a 2,500 mile trip over the next 5 days. Hoping I don’t end up in throttle mode limping down the highway because this sensor is off. Any way to reset the sensor?

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cNate · July 1, 2020

I also have a 2020.

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gjohnston7 · July 1, 2020

Take it in to the dealer. It is my understanding that they have two different software upgrades that help with the sensor. It improved the accuracy for me but it is still a long way from perfect. It sure is looking like the 2020 Silverados are getting 300-400 per gallon of DEF. I wish that GM would just come out and say that is going to be how it is if that is really what the expected performance is going to get. I hate the thought of buying a Ram or Ford but this isn't going to work for me. I worry about being caught in the middle of nowhere as well.

The dealer said the cheese cloth test is for something different and won't address our issue so no go there.

hotairgypsy · July 3, 2020

Was at the dealership today for an error code and when i got my truck back they said there was a recall on the def system and they took care of it while I was there...They said it was something to do with reengaging the def cycle ....didnt sound like it was anything that would help the cause...I am on the road in the morning so if i notice anything i will post up

cNate · July 8, 2020

Just brought the truck in for oil change, DEF top off, tire rotation, and replace the fuel filter (at 29% after 12k miles). Lots of towing so not getting anywhere near the 18-20k it’s expected to last.

I asked them to check DEF system for recall or SERVICE BULLETIN and they found a software reprogram. They think it’ll help with the sensor reading the levels accurately now. I was having a problem where I fill up and it shows it was still half empty for a few hundred miles. My concern is more with the sensor because if the truck thinks it’s out of DEF and it’s not, then my speed will be limited. Sometimes it was showing full immediately. Software update likely won’t help with mileage. Techs thought 300-400 miles per gallon of DEF while towing was on par with what they’ve seen. Will report back after I put another 1k miles or so on the truck to let you know if it helps with sensor or burn rate. See bulletin number below.

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gSwift · July 9, 2020

I seem to have the opposite problem with the DEF. I have a 2 week old 2500 AT4 Duramax and it has about 1600 miles on it and the DEF level hasn't moved off of full. This is my first diesel so not sure if thats normal given the mileage on the truck

cNate · July 9, 2020

Likely your sensor is not working. I bet you could get 2-3 gallons in there if you fill it up.

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gSwift · July 9, 2020

17 hours ago, cNate said:

Likely your sensor is not working. I bet you could get 2-3 gallons in there if you fill it up.

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When I got it home from the 425 mile trip from buying the truck, the DEF tank was half empty, so I topped it off then. So it was filled at about the 500 mile mark and since that point it hasn't moved. Which means I've put 1150 miles on it and the DEF gauge hasn't budged.

I'll try to add some and see if it takes it. Talked to the dealer today and they said they hadn't see any where the DEF gauge wasn't dropping, only that the low DEF indicator was coming on prematurely.

cNate · July 10, 2020

When I got it home from the 425 mile trip from buying the truck, the DEF tank was half empty, so I topped it off then. So it was filled at about the 500 mile mark and since that point it hasn't moved. Which means I've put 1150 miles on it and the DEF gauge hasn't budged.

I'll try to add some and see if it takes it. Talked to the dealer today and they said they hadn't see any where the DEF gauge wasn't dropping, only that the low DEF indicator was coming on prematurely.

Let us know how much you can get in there and if you’ve been towing. Dealership claimed upwards of 1k miles per gallon not towing. I’m surprised your dealership didn’t know about the service bulletin to reprogram the module. Could be because mine was manufactured last summer and purchased in October.

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gSwift · July 10, 2020

1 hour ago, cNate said:

Let us know how much you can get in there and if you’ve been towing. Dealership claimed upwards of 1k miles per gallon not towing. I’m surprised your dealership didn’t know about the service bulletin to reprogram the module. Could be because mine was manufactured last summer and purchased in October.

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Haven't towed anything yet. And as far as the dealer goes, all I did was called one of the service advisors on the phone...maybe i'll take it in one day.

Thanks for your help