3.0L Duramax D.E.F. Gauge Issues?

[MrMike1289]

Recently while towing I had roughly 1/4 of DEF fluid left per the dash gauge. While we were towing, the message popped up letting me know I had roughly 270 miles left before empty on the DEF.. roughly 10-20 miles later another indicated came and told me I was critically low and it will start limiting my speed soon. I checked the gauge again and it was on empty. Could this potentially be an issue somewhere regarding my DEF gauge? After putting about 2.5 gallons in at the next gas station, and a bit further down the road, the same notice popped up telling me I had 1000 miles left. I found it a bit odd this message also popped up again after fill but maybe that’s normal. However, the gauge dropping so suddenly like that was a bit concerning/alarming. If I wasn’t close to a station I would have been SOL.

 

[TollKeeper]

Per GM, the DEF will be used at a 4x rate when towing. Never got an explanation why..

 

[MrMike1289]

Per GM, the DEF will be used at a 4x rate when towing. Never got an explanation why..

Interesting to hear. The math still doesn’t add up but I figured it would consume more when towing. I did consistently check after I filled it to see how much it would move the rest of the trip but the gauge never budged for another 200 miles.

 

[Stbentoak]

I believe the sensor in this tank is not exacting like a "Float" type measure, but more like a "Sensor" type device. it is unexacting at best. Especially when towing, if you are under 1/2.... Fill it at next fuel stop for no worries....

 

[Ckarr]

Hey y’all. I’m new to the forum even though I’ve stalked y’all for years. I’ve got a 2021 Sierra elevation with duramax. I have 17,000 miles and my check engine light came on. The dealership wasn’t exactly sure and said they would need to get it on a lift and expect it. I noticed the def gauge was still completely on full even though I knew it had to be almost out. Sure enough I fill it up and two days later the light is off. I’ve been driving another few hundred miles now and the def gauge still says full. They told me it’s not like a float bowl but it measures and approximates differently and each time the vehicle starts and stops and other junk that makes no sense to me. I’m sure it’s just a sensor they may need to replace

 

[MrMike1289]

Hey y’all. I’m new to the forum even though I’ve stalked y’all for years. I’ve got a 2021 Sierra elevation with duramax. I have 17,000 miles and my check engine light came on. The dealership wasn’t exactly sure and said they would need to get it on a lift and expect it. I noticed the def gauge was still completely on full even though I knew it had to be almost out. Sure enough I fill it up and two days later the light is off. I’ve been driving another few hundred miles now and the def gauge still says full. They told me it’s not like a float bowl but it measures and approximates differently and each time the vehicle starts and stops and other junk that makes no sense to me. I’m sure it’s just a sensor they may need to replace

Hmm. That’s interesting to hear! Thank you for sharing. I’m keeping my eye on it for sure. Sort of waiting to see what happens this next time I get low on DEF fluid since I’ve just filled up. Hopefully it was a one time thing but we shall see!