3.0 Duramax DEF consumption

[topgear1224]

most large truck stops have it set up at pump. ($2.99 gallon in our region) I built a rack in my enclosed trailer to hold 2 boxes. Keep it in house where cool till get ready to go (lasts longer in cool areas). It is more of a nuisance than a problem, but I do think uses too much.

we don't have DEF at the pump here in Alaska cheapest you can get at least in Fairbanks, is about 10 bucks a box for the supertech but they constantly sell out and then you have to pay 17.99 for a two and a half gallon of box of PEAK.

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[yousaveone]

Same thing, hardly used and def until 9K now twice as much if not more. Scheduled for recall on Wednesday. I asked what they were going to do; sounds like another ecm reprogram. 

 

Curious because it was never an issue until my free wifi took affect. Is GM doing software upgrades via wifi remotely?

[topgear1224]

Same thing, hardly used and def until 9K now twice as much if not more. Scheduled for recall on Wednesday. I asked what they were going to do; sounds like another ecm reprogram. 
 
Curious because it was never an issue until my free wifi took affect. Is GM doing software upgrades via wifi remotely?

the system is designed to save you from yourself so if you put 9,000 miles on and used very little def the system's going to automatically adjust itself to begin again consuming more so it doesn't spoil, gunk up and cost you out of pocket.

Just a theory. But considering most of the buyers of this engine this will be their first diesel it would make sense for GM to do something like that similar to how they did with the fuel filter life.



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[Moab4x432]

I have 9500 miles on my 3.0 right now

i burned through 5 gal of def in the first 7800 miles.

i took the truck in for the first oil change and they did a “recall” because the def system was inoperable. After the computer flash I have burned through 10 gal of def in 2600 miles 

wtf did this recall do to my truck?

[topgear1224]

I have 9500 miles on my 3.0 right now
i burned through 5 gal of def in the first 7800 miles.
i took the truck in for the first oil change and they did a “recall” because the def system was inoperable. After the computer flash I have burned through 10 gal of def in 2600 miles 
wtf did this recall do to my truck?

Is there a TSB # listed on your service ticket? I'm trying to figure out what DEF recall there is

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[Moab4x432]

3 hours ago, topgear1224 said:

Is there a TSB # listed on your service ticket? I'm trying to figure out what DEF recall there is

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[topgear1224]

 

Hmm can't find any info on that TSB other than the title. "Diesel exhaust fluid system inactive" (not paying $15 to access it)

So if the system was not injecting any def previously that would be why your def consumption went up.

Here is their explanation from April 2020. Looks like they are using calibrations for future NOx guidelines.

"Under certain conditions, the ECM will increase or decrease the amount of DEF used based on learning or adaptive algorithms."

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[Benzo1]

On 6/26/2020 at 9:38 PM, Moab4x432 said:

 

So at 3,400 miles my 3.0L Duramax check engine light came on.  I scheduled an appointment with GMC to have it looked at.  Upon picking up the vehicle was told it was related to a recall.  After reading your post and looking at your service ticket I have the exact same Service Update Bulletin (N2023000791).   Since the update my DEF consumption has nearly doubled.  

[Grover67]

Took off last Sunday for vacation, filled truck and topped off DEF before leaving. About 45 miles into trip check engine light came on, scrolled around my info screens and found my DEF gage reading empty or not registering, DEF gage came and went but would either read full or nothing at all, engine light came on too. After 600-700 miles into trip the check engine light came and went also, and after about 1200 miles pretty much has stayed off. Came home after putting  on 1700 miles, topped off DEF to see if it used any, it did use about a quart. Ran fine the whole time 27mpg on first tank and 29mpg the second. It does have some kind of drivetrain vibration about 65mph that has been there since new, figured it would go away with some miles, hasn't.

 

Monday morning called dealer that next door to where we stayed to have check engine light looked at and he politely said he could sometime on Wednesday........passed on that overstay

 

-grover67

Edited July 12, 2020 by Grover67
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[Rubyralph]

My dealership filled my DEF tank when I took delivery of my new 2020 Silverado 1500 3.0 Duramax, I now have ~1800 miles on the truck and the DEF gauge still reads full, when will I see a drop on the DEF gauge? Mostly highway miles not towing yet, average mileage 27.9 to 29.1.

Love the truck but I'm starting to wonder about my DEF usage???

[redwngr]

5 minutes ago, Rubyralph said:

My dealership filled my DEF tank when I took delivery of my new 2020 Silverado 1500 3.0 Duramax, I now have ~1800 miles on the truck and the DEF gauge still reads full, when will I see a drop on the DEF gauge? Mostly highway miles not towing yet, average mileage 27.9 to 29.1.

Love the truck but I'm starting to wonder about my DEF usage???

My 6.6 gets 11 or 1200 miles per gallon def.

 

I'd expect that with the fuel mileage you're getting that your's would easily be 1500 miles per gallon. 

When you get to say 5000 miles, fill it at a bulk pump and do a hand calc.

You'll have mpg, will know about how much was remaining in tank, and what the indicator was reading at that stage. 

 

Def indicator / LED display is a new thing for the 3.0 and the 20+ HD's.

It's not a traditional gauge with a float.  

 

https://gm-techlink.com/?p=13143

 

 

[topgear1224]

Here is GM's executive chief engineer for full size trucks.

"About an oil change interval is what we shoot for"

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[redwngr]

22 hours ago, topgear1224 said:

Here is GM's executive chief engineer for full size trucks.

"About an oil change interval is what we shoot for"
 

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Daily driver -- sure.

Not gonna happen on a truck that tows (or other work that results in higher fuel consumption) 

Edited July 14, 2020 by redwngr

[topgear1224]

Well oil changes are determined by load and oil temps.

I know mine shows 1.5 gallons (25.5% remaining) till completely dry and I filled up 3416 miles ago.
Used 150 gallons of fuel in that time.

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[Dan Southworth]

Having similar issues with very high DEF usage, Just bought the truck last month primarily to tow 25 ft travel trailer (4700 lbs  dry, est 5700 lbs loaded). On our first trip with travel trailer from our home in The Villages to Pensacola, 400 miles.  Not long after leaving the house got a message stating we had 2000 mile range on the DEF. Checked gauge and it showed 3/4 full.  Just on the other side of Tallahassee, roughly 250 miles into the trip, message came on the we had 300 mile range,  Gauge showed 1/4 full.  100 miles later, 50 miles from Pensacola, warning came on stating DEF tank was empty.  Bought DEF once in Pensacola and filled it for trip back to The Villages.  Same problem on the return trip, used up entire Def tank on 400 trip.  Difference this time was when DEF ran dry max speed was immediately reduced to 65 mph.  I estimate that I used about 8 gallons of DEF for the 4 day 1000 mile trip, 800 of that towing.  DEF usage calculation was 1 gal of DEF for every 11 gal of Diesel.  Significantly higher than what I was told DEF usage would be.  During the entire trip the check engine did not come on.  The check engine light finally came on the following day when not towing the trailer. Took vehicle to dealer and they have diagnose a faulty particulate sensor.  Problem is the part is backordered with no estimated time of delivery.  Have been told not to do anymore towing until part has arrived.  Reading through other threads, it appears this engine might had not been tested fully under towing conditions.  Emission systems appears to be overcompensating when fuel usage increases when towing,  I have experience minimal DEF usage when driving truck not towing,