This is from the "2020 Diesel supplement" but yours should be the same (you can verify in your diesel supplement)
(bold is my editing)


DEF Low
As the DEF level drops, warnings will automatically be displayed in the
Driver Information Center (DIC).
Select Vehicle Information in the DIC to view DEF level status.
See Driver Information Center (DIC) pg 12.

Refill the DEF tank at the first opportunity after a low warning indication to avoid vehicle speed limitations.
It may take some time for the vehicle to detect that DEF has been added. If there was a vehicle speed limitation, it will be removed gradually and it may take several kilometers/miles for the DIC message to update.

If DEF is added under freezing conditions, additional time may be required to remove speed limitations.

The DEF range DIC message first displays at approximately 1 600 km (1,000 mi). This message appears again at approximately 500 km (300 mi) of remaining range before the exhaust fluid tank becomes empty.

As the fluid level nears empty, these messages appear every time the vehicle is started.
If the DEF low warnings are ignored and the DEF tank becomes empty, the DIC will display messages that
describe the action needed and distance until vehicle speed is limited.

For the DEF warning light symbol, see Diesel Exhaust Fluid (DEF) Warning Light pg 11

 

Definitely not normal on a 22. My 22 definitely gives me the warnings before hand. I have never ran it empty but I have gotten the 1000 mile warning on multiple tanks.

 

Well they filled it up today. I’ll be watching it. I never got a warning I’m at 7300 miles

 

It's better to keep it filled and never have the warning system come into play.

 

I usually wait til the miles to empty warnings start before adding DEF.
Both the '18 L5P and '21 LM2 I've taken to the 'DEF Empty' message, when it will warn that 65 mph speed limit starts after 500 more miles.

This pic is LM2.
Miles to speed limit does a mile-by-mile countdown that cannot be cleared.
Happened to be half full of fuel, so it's gonna need fuel before the speed limit.

 

So I'm driving a 2022 GMC SRW 3500, not my 1st diesel but 1st with DEF - Being a new truck I have been monitoring everything close! I noticed my DEF gauge appeared stuck just over 1/2 full for over 500 miles. I decided to put 2.5 gallons in before I had to go on a 300 mile trip just to be sure I didn't run into any issues. After I put it in, gauge read full. 20 miles down the road the gauge dropped 1 tick below full. Truck only has 8k miles and it wasn't the first time putting in DEF, I'm hoping it was just a glitch that had it stuck but will monitor. Anybody else seen this?

 

The DEF gauge on the DIC isn't great. If you get an iDash you can see the actual % of the tank. It moves a lot though since the sensor isn't great so it is only really accurate when stopped on a level surface.

I would highly recommend getting an iDash.

 

Those that ran 2011's learned to operate without any 'level indicator' and just make use of the 1000 mile and 300 mile warning.

At the 1000 mile warning its gonna need fuel before the def is empty.
Where there is fuel, there is def. (wasn't always the case when def was first put into use)

If it does reach empty, there is a 'miles to speed limit' warning that gives another 500 miles before the first speed limit.

Some of us run them down just to see the message. (post #6)

 

2022 Sierra 2500 HD - 38663 miles DEF Completely empty, and zero warnings .. i’m not complaining or anything lol but has anybody seen this happen besides me?

 

2022 Sierra 2500 HD - 38663 miles DEF Completely empty, and zero warnings .. i’m not complaining or anything lol but has anybody seen this happen besides me? View attachment 1121654

Last (partial) segment isn't out yet.
It's close to empty.

 

I started this thread. Mine has yet to give any warning or low messages. The manual says it should.

 

I started this thread. Mine has yet to give any warning or low messages. The manual says it should.

10-4 like I said I’m not mad about it for obvious reasons lol just found it odd, my 2018 duramax would have had a fit in the same situation.

 

Same here. Have had my 2022 since new (3 years old this coming October). Always got warnings and always filled it. Just realized I hadn’t added in a while, checked the gage, completely empty, no warnings, no speed limitations. Added 2.5 gallons, gage went to 1/2. Odd never got warnings, etc. not sure if any damage was done, but with 38,900 miles, I’m out of warranty so I’m not taking it to dealer to check unless I have issues.

 

Just FYI; your emissions system warranty goes to 80k miles. So if you’re having issues with the DEF level gauge, and especially if you’re getting low warnings when you’re DEF is full, it’s covered until 80k miles.

I’ve had my DEF tank replaced TWICE and the associated harness replaced. All under warranty.

 

On all the diesels that I have owned(Ram/Ford) that have taken DEF, none of the DEF gauges have been very accurate in terms of how much DEF was left in the tank. I always added a jug once it got below half of a tank. I have noticed that the gauge in my 2024 Silverado has a mind of its own, in fact on a 1200 mile trip I filled it and the gauge never really showed full. It seemed to not move for about 800 miles then it just dropped to in between half and 1/4 after stopping for fuel in one shot, never gradually really. Then it actually went back to almost full again briefly and then back down to half.

People tend to have issues when they allow the DEF tank to run empty it seems. Either they start having clogged DEF injectors or other DEF error codes it seems like. Its best always have DEF in there and not allow it go to low where it may start to crystalize at the bottom(just a guess). Its best kept wet!

 

I've been reading/following GM dmax forums since before DEF came into use. (other forums longer than this one).
I don't buy the argument that def problems are because the tank is allowed to get low.

I've noticed there are posters that seem confuse the 'service emissions' warnings and countdowns with the def level warnings. Both can lead to a lower speed limiter, but with different steps/warnings to get there.

With the LML, I regularly waited for the 300 miles to empty warning to add def, and always waited for at least the 1000 miles to empty warning. ( LML did not have the dic page with would show approximate def level when it was less then 30%. It only gave had the 1000 mile warning once, and then the 300 mile warning. It would update the the miles to empty when restarted. )

With L5P, LM2 and LZO, I regularly take def tanks to empty....just to see the 'miles to empty' warning progression and then when it says it's empty to see the 'miles to speed limit' counter.

These pics were with on my 2018 L5P.
The 'miles' will countdown mile-by-mile as it is drive.

 

I've been reading/following GM dmax forums since before DEF came into use. (other forums longer than this one).
I don't buy the argument that def problems are because the tank is allowed to get low.

I've noticed there are posters that seem confuse the 'service emissions' warnings and countdowns with the def level warnings. Both can lead to a lower speed limiter, but with different steps/warnings to get there.

With the LML, I regularly waited for the 300 miles to empty warning to add def, and always waited for at least the 1000 miles to empty warning. ( LML did not have the dic page with would show approximate def level when it was less then 30%. It only gave had the 1000 mile warning once, and then the 300 mile warning. It would update the the miles to empty when restarted. )

With L5P, LM2 and LZO, I regularly take def tanks to empty....just to see the 'miles to empty' warning progression and then when it says it's empty to see the 'miles to speed limit' counter.

These pics were with on my 2018 L5P.
The 'miles' will countdown mile-by-mile as it is drive.

View attachment 1134387


View attachment 1134386

Some people play with fire and just haven't been burned yet.

 

Recently ran mine as low as I ever have. Bar was red, notification that DEF needed refilled, etc. Only received the 1000 mile warning. When I filled it up at the pump, it only took 5.3 gallons. Meaning that there was over 1.5 gallons left in the tank.

Using up DEF until you get a speed warning is absolutely acceptable, like @redwngr mentioned.

 

It doesn’t bother me so much that the DEF level gauge isn’t precise. My RV’s holding tank sensors aren’t precise either. What bothers me is that that it “thinks” I’m about to run out of DEF when the tank is actually full. And then it threatens me with limiting my speed, and potentially limp mode. -That’s the bigger issue here.

It’s ridiculous. DEF has been around long enough that the related sensors and injectors and heaters should all be working without any worry from the operator/owner. It’s just water and Urea. And it’s just for the emissions system.

 

It doesn’t bother me so much that the DEF level gauge isn’t precise. My RV’s holding sensors aren’t precise either. What bothers me is that that it “thinks” I’m about to run out of DEF when the tank is actually full. And then it threatens me with limiting my speed, and potentially limp mode. -That’s the bigger issue here.

It’s ridiculous. DEF has been around long enough that the related sensors and injectors and heaters should all be working without any worry from the operator/owner. It’s just water and Urea. And it’s just for the emissions system.

Yes!

Imho, the biggest issue is the crappy job they have done with the level sensing and and the warning escalation system.

 

If it was going to be an issue, GM would put something about it in the manual.
15 years of DEF operation and they haven't found a need to do that.

If it was a problem, GM also could also have adjusted the level indicator so it isn't really empty when it says it is.

 

You can do as you wish with your truck, but DEF, EGRs and DPF are not good for our trucks, If you ever seen the inside of an EGR you know it can't be good.

If you ever see a military diesel truck you will see they have no DEF etc...in fact I have seen some government diesels that are not military absent of all DEF, EGR etc....


They know it's all BS....

Do as they say not as they do..

 

You can do as you wish with your truck, but DEF, EGRs and DPF are not good for our trucks, If you ever seen the inside of an EGR you know it can't be good.

Didn't say any of them were 'good' for our trucks.

I thought we were discussing whether the def level could be run down or not?

And, fwiw, soot not the same as the NOx that is reduced using DEF.

 

You're still mixing apples and oranges.

 

No iam multi tasking.

Don't run your DEF tank empty..

Absolutely no reason or benefit to it.