Home Forums Gear Hunting Trucks and Four-Wheel Drives DEF question

My new Chevy Duramax manual says that DEF additive freezes at 14 degrees F ,and it would need to be taken into a warm garage until it thaws.My garage is unattached and not heated. Will it thaw once the truck is warmed up from running.The DEF reservoir is under the passenger side frame?.Here at 7650 feet elevation, winter temps hit below that frequently.

What is the solution to this problem? Thanks

It's my understanding that it has a DEF tank heater and the tank is insulated. I read somewhere that it also has a pump to empty the lines when you shut it off. The DEF system will shut off when it freezes and then kicks back in when the heater thaws it out. They recommend that you not keep the DEF tank full. As it freezes, it expands like water and can damage the tank if it's too full.

Here's an excerpt from one article I saw:

HOW TO PREVENT DEF FREEZING?
DEF freezing was taken into account by the OEMs prior to creating the Selective Catalytic Reduction (SCR) systems. Therefore, the SCR systems are designed to provide heating for the DEF tank and supply lines; however, if the vehicle is shut down and exposed to freezing temperatures, then it is likely that the DEF will freeze. Diesel owners do not need to worry about DEF interfering with their vehicle, however. If DEF freezes when the vehicle is shutdown, startup and normal operation of the vehicle will not be inhibited. In most cases, the SCR heating system will quickly thaw the DEF in order to return it to liquid form and resume normal operation.

Thanks.
I figured there was something,but the manual doesn't cover anything.
My tank holds 7 gals and they put two in when doing the initial new vehicle check.I'll probably add enough to make it 5 gallons

It has to have a heater Vince, for exactly the reason you have. You should get a message if the heater goes out.

What year duramax? And what happened to your dodge?

I believe the system is similar to my ram. There is an electric heater and while the DEF fluid can freeze below 12 deg, once the ignition is on it sends juice to the heater that then thaws the fluid in the tank. It has been reccomended not to keep the tank tip top full in extreme cold weather.

2019 Duramax. Dodge had a lot of repairs this summer. Got tired of stuffing money in it. I'll probably sell it after the 1st of the year

I have a duramax, 2011, and try to start the winter with about 4 or 5 gallons. I have not had an issue with def freezing. I have had this truck since Oct. 2010. Like has been said the tank has a heater and def will expand when frozen. I am not at your elevation but it does get cool here in Mn.

This is a new truck and the DEF tank is full. I doubt I can use a gallon or so before really cold weather hits.Wonder if there is a way to siphon some out?

I'm sure it has a heater in the tank. I'm not sure about a Duramax, but heavy trucks have a heater in the tank, and when you turn it off, the lines drain out and return the DEF to the tank.

If you're storing DEF in a can or bottle in your garage, I'd bring it in the house so it doesn't freeze solid.

I'll add to that and say the DEF has a shelf life that varies according to the temperature that it is stored at. The higher the temperature, the shorter it's life. It can be checked with a refractometer designed for DEF. Old DEF will cause malfunction warnings as there is a DEF quality sensor in the system. So don't be tempted to stock up on it.

Manual says a tank of DEF should last about 7500miles,about what an oil change is.I put about that many miles on in a year. Should be good for that,Yes?

Not storing any.

Probably better to add 2 gallons at a time then. We've had DEF in the shop start to go off after 6 months when stored in the summertime with temps of 80-95 degrees.

The DEF is used by the amount of exhaust going through your motor. If you are pulling something your DEF gets used up quicker than if you are running empty. With my 1 ton RAM it seems the DEF dial doesn't move, but when I haul my trailer it almost seems like you can watch it go down.

Also I have never got more than 3000 miles with DEF when empty.

If the dealer filled the def tank I would bet they didn't any more than 5 gallons in it. I have gone almost a year one one def fill up with no def quality issues.

Yea,they only put 2 gallons in it,but the manual said to fill it which I did BEFORE I knew it would freeze.Now I have 7gallons in it with temps suppose to drop this week. Probably have to put a heater under it somehow.Taking it too the dealer tomorrow for post sales work. I'll see what they say

Trust me that def will not freeze unless you let it sit for days and not drive it, a bunch of Chevy,gmc,dodge, fords up here in Alaska running def to include me when I owned a diesel never had it freeze.

It froze unless parked in a heated garage.

It will run fine while the heater thaws the def, then start injecting it.

We're those open jugs?

ANY idea of shelf life for a sealed, new jug?

Here's what I found.

Just had a problem with 10 of our Cummins the other day. Had a code come up and it said low quality DEF . Come to find out with the the new refractometer our DEF had to much urea in it. We get it in Bulk waiting to here back from supplier. We drained 2 of them out and put the Blue DEF and engine lights went out and back on road. Tested new batch and was just under 32.5 so we topped off rest so far so good.

I guess living in the valley does have its advantages.. my def never froze...

Never colder than +12? Really is the banana belt.

Do a full delete, then you never have to screw with that idiotic EPA DEF fluid gain.

That would void the warranty on a new truck

Absolutely...

and kiss your chances of ever having a shop work on it if you need it. If you can do all your own wrenching, not a big deal.