DEF Gauge stuck???

bonzman17 · April 24, 2021

I just turned 10k miles. I am thinking the float for the def gauge on my truck is stuck in the full position. It’s been at least 3k miles since I topped it off and I’ve smelt 2 regens but the level according to the dic is still full. It’s hard to believe that this uses such a minimal amount per regen.

I’ve been on some bumpy roads and I have heard the fuel sloshing in the tank so I would imagine the def would be doing the same. Just wondering if anyone else has had the same issue. Think I’ll craw under it and tap the def tank (if I can get to it) with a dead blow a few times.

bonzman17 · April 24, 2021

FYI. The def tank is above the fuel tank. Can’t get to it unless you drop the fuel tank.

redwngr · April 25, 2021

DEF is used whenever the engine is running.

It is NOT a regen only item.

During regen, the truck adds fuel directly to the exhaust to create the regen heat. It will add some extra DEF to respond to the extra NOx produced burning the extra fuel.

If it's been 3000 miles since it was filled and the gauge still has all the LED's lit I'd agree it's probably not displaying correctly.

Checked my gauge today.

4600 miles since it was filled and it has 3 of the LED's off (above the 1/2 mark there is still one lit -- book says it will hold 2 gallons after the next one goes out)

iDash reports the level bouncing around 48-51%. (I'm expecting the next LED to turn off soon)

Regens on this 3.0 are much more frequent than the were on the 6.6's I ran.

They are also much shorter duration.

It's usually somewhere in the 260 - 320 mile range between regens and they are lasting 10 - 13 miles running 2 lane highway speeds.

Having said all that I'm not sure the def display is super accurate -- I'd expect it to have a least a couple of LED's turned off by now.

Unless it's working really hard and using lots of fuel, it also be surprised if it needs def at 3000 miles.

I'm expecting somewhere around 9000 miles til it tells me it's empty.

Current plan is to run til it's empty and it starts giving the ' xx miles til speed limit' warnings.

bonzman17 · April 25, 2021

Thanks for the reply. I’m honestly waiting for the speed warning to come on at some point since there’s been zero change on the level. Wish they would put some kind of indicator while in regen.

steve841 · April 25, 2021

I wouldnt lose sleep. Maybe you'll find the "fix" for needing to add def ...

Worst case, you'll get the 55mph warning and you'll know a trip to the dealer is in order.

Edited April 25, 2021 by steve841

Sqrls · April 25, 2021

2.5 gallons of DEF averages me around 3500-4500 miles. My first tank of DEF was used in 6400 miles, but my def use has slightly gone down. I have 35,000 miles on it already. I normally always have at least 1,000 lbs in the bed with mixed city/hwy driving and pull a trailer pretty often. Normally, I just add 2.5 gallons when it gives me 500 mile warning and it lasts 3500-4500 miles. 2.5 gallons from empty takes me 1-2 bars from full even though it’s only half a tank.

bonzman17 · April 25, 2021

Thanks. I usually do not have a load. Seems like crystallization would become a problem at that rate no? Just seems like it’s been to long since the level dropped compared to the colorado I had. I’m going to see if obd2 fusion app I used to monitor on the colorado has the pids for the Silverado.

redwngr · April 25, 2021

If the level is detected the same way as in the LML def tank, then it's not a float -- it's a series of pin sensors, and a bunch of software to estimate the level between the sensors as well as to prevent the display from jumping around when the def sloshes.

redwngr · April 25, 2021

2 hours ago, bonzman17 said:

Thanks. I usually do not have a load. Seems like crystallization would become a problem at that rate no? Just seems like it’s been to long since the level dropped compared to the colorado I had. I’m going to see if obd2 fusion app I used to monitor on the colorado has the pids for the Silverado.

I don't think crystallization inside the tank is going to be an issue.

Imho, wait for the 1000 mile to empty warning, and/or the 300 mile to empty warnings, and then add some.

The countdown for speed limiting doesn't start till it's reaches empty -- and the first warning is 500 miles to 65 mph. Lots of time from the first 1000 mile to empty warning to get def.

When I ran an LML my location didn't have a convenient bulk def nearby.

Most others reported that the tank would hold 2 of the 2.5 gallons jugs when the truck gave the 300 mile warning. Mine wouldn't take all of the second jug. Meant managing a part jug and remember to later add the balance of the second jug later.

Switching to buying/adding one jug at a time made it simpler. Did that for a bunch of years without 'crystallization' from a part full tank.

Ross McKenrick · July 19, 2021

I think this is a software problem. I work for Microsoft and I just bought a new 2022 Chevy Silverado 1500 with a 3L diesel engine. We are on our initial cross-country trip towing a 4000 lb RV trailer. With 2500 miles on the speedometer, we have been through 5 2.5 gal bottles of DEF (in addition to what was in the truck when we pulled it off the lot).

With a 5 gal DEF tank, I expected to be able to empty at least a 2.5 gal bottle of DEF into the tank when the tank was approaching empty. But no. Like the previous person, when the gauge says the DEF tank is empty, I am only able to add 2 gal of DEF before it overflows and makes a mess.

I am completely confused by the message that says DEF empty and I have 500 miles before I am speed limited.

I am convinced that the DEF tank is not empty, but I do have 500 mikes of range left. Yet I have to endure this dire message which takes over the dashboard screen for some 20 miles or so and then goes away.

Meanwhile, the DEF level screen has only two readings, 7/8 full and empty.

We need a software update. We need a better user experience so that we can live with this DEF system.

aangulo1 · February 4, 2022

I have a 2021 GMC Elevation DURAMAX 3.0..... Around 7K on it.... After all being okay, suddenly the DEF gauge started to act weird. It happened after it gave me a low warning. After that and before putting DEF in it, the gauge showed half tank. Decided to fill one jug (2.5 gal), did not move........ After several miles now it was showing full!! Very frustrating. Decided to put the other 2.5 gal in it. It has been 2k miles and still showing full...... Took it to dealership and this is their response: "NO PROBLEMS FOUND, CONDITION IS NORMAL; DEF CONSUMPTION DEPENDS ON ENGINE LOAD, FUEL USAGE, HUMIDITY TEMPERATURE AND IS NOT MILAGE BASED. DEF SYSTEM WARNING WILL APPEAR SHOULD AN ERROR OCCUR"

So how is it that before, that DEF gauge will show different levels as the miles grown and now is not? Is GM Tech just giving me some quick response so to not troubleshoot the fault?

Thanks

eckseleven · February 4, 2022

The thing with the DEF gauge is that you have to think about it like the "miles to empty" that we have with fuel. It is purely an estimate and that estimate will change based on usage. If your vehicle usage changes suddenly, it takes time for the gauge to reflect that.

For me it hasn't been a concern so far. When I'm towing I'l just note what it predicts I have left and pack a jug accordingly. You start to get a feel for it after a while.

gobbledott · April 19, 2022

I am new to def but similar problems. Mine was filled by the dealer and only showed about 1/3 on the vertical scale and showing def ok. First warning came showing 525 miles left, followed by one at 225 miles showing def low. Gauge never moved. Put in 2 1/2 gal. still no movement. Talked to the dealership and the guy tried to convince me that there was no gauge there. I will be dropping in to see him in person. Anyone with a similar problem ? 2019 Silverado, duramax diesel

Ckhris · February 21, 2023

On 7/18/2021 at 10:37 PM, Ross McKenrick said:

I think this is a software problem. I work for Microsoft and I just bought a new 2022 Chevy Silverado 1500 with a 3L diesel engine. We are on our initial cross-country trip towing a 4000 lb RV trailer. With 2500 miles on the speedometer, we have been through 5 2.5 gal bottles of DEF (in addition to what was in the truck when we pulled it off the lot).

With a 5 gal DEF tank, I expected to be able to empty at least a 2.5 gal bottle of DEF into the tank when the tank was approaching empty. But no. Like the previous person, when the gauge says the DEF tank is empty, I am only able to add 2 gal of DEF before it overflows and makes a mess.

I am completely confused by the message that says DEF empty and I have 500 miles before I am speed limited.

I am convinced that the DEF tank is not empty, but I do have 500 mikes of range left. Yet I have to endure this dire message which takes over the dashboard screen for some 20 miles or so and then goes away.

Meanwhile, the DEF level screen has only two readings, 7/8 full and empty.

We need a software update. We need a better user experience so that we can live with this DEF system.

LOL, you work for Microsoft so that is supposed to make us believe you are an expert on GM coding… give me a break… no one cares where you work

SPASierra · February 22, 2023

18 hours ago, Ckhris said:

LOL, you work for Microsoft so that is supposed to make us believe you are an expert on GM coding… give me a break… no one cares where you work

You replied with that $htty remark to a post from 2021?! You must be really bored. Be a better human.