Refill DEF soon on OnStar

[ctdeng0]

Just bought a 2023 Yukon Diesel and the OnStar app say status DEF range. Refill soon. The vehicle DIC shows the tank at 50%. Is this normal?

 

[OR VietVet]

Welcome to the forum from Oregon

The DEF warning does make sense. Just like fuel in the tank. You should not wait till close to empty to refill. I always tell people to think of 1/4 tank as empty. The DEF warning is doing the same thing. You never know when you need DEF and it may not be close to where you are at, at that moment. Top off when you can.

 

[Stbentoak]

No, it does not make sense. Half full (If truly half full) means you have at least 2-3000 miles of range left. I believe there is a software update out there for erroneous DEF readings. The least of which you should trust is Onstar warnings.
If things are working as they should you should get a warning on the vehicle DIC with say roughly 1000 miles range left to go. Kind of like a preliminary warning. Then at 500 miles to go, it gets a little more serious and starts counting down to zero. In most cases, I drive my vehicle until I get the first warning. Then dump in two and a half gallons from Walmart and motor on.
The only time the above rules don't apply is when you are towing with the vehicle. If you are towing, especially somewhat heavy, it takes down DEF at 2 or three times the rate of normal driving without a load.

 

[Big Bad Allis]

Depends on the vehicles history. Since you just bought it, you don't know it's past job. If it pulled a trailer a lot, the DEF range and expected refill is much shorter.

 

[Stbentoak]

What it did "Previously" has nothing to do with what it's doing or how it consumes currently. DEF level is a reflection of current state, not what it did 2 months ago......OnStar warning is erroneous. I wouldn't count on anything that they warned me about without substantiation from an OBD scanner.....

 

[Big Bad Allis]

If will use historical data to project added fluid needs. Just like oil, your oil life indicator does not analyze the oil. It uses time/dates and actual operational data to calculate your %.

 

[ctdeng0]

I will note that the trailer hitch looks like it was never used. All the paint looks new and the safety chain hooks have no paint missing.

 

[ctdeng0]

UPDATE: I filled the DEF tank and the Onstar app still shows the warning “diesel fluid Range Low” “speed may be limited”. I have only driven a couple of miles since filling the DEF tank.

 

[ctdeng0]

Update: opened a ticket with OnStar for this issue. OnStar confirmed this is a issue with more than my vehicle and they will update me once they have a solutio.

 

[CTown Duramax]

Don't know if this helps, but I have only gotten the warning when the system tells me range is below 1,000 miles.