Def fluid question

[rodgers51]

1st time on forum owner of a 2019 3500 draw limited After 100 miles my DEF see dealer light came on shortly after that can the notice you have 150 miles it shuts down to 5 mile an hour. took it to the dealer they said the def was overfilled and drained 2 gallons so now my gauge is between Full and 3/4. Is there such a thing as overfilling the def tank if so how do you not overfill it. I would have thought they would have filled it properly and see what would happen to determine if I have a bad sensor. Anyone with thoughts

 

[mtnrider]

Never heard of anyone getting an error from over filling, I'm calling BS on that. Maybe it was some bad DEF in there causing the error and draining it cleared it?


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[Jeremiah walker]

Interesting...I have a '14 3500 and this is my recent experience with my DEF tank..
About 4 months ago, I used a pump at a gas station to fill my DEF up. It clicked off just like a gas pump mind you. I grew concerned after driving around 4k miles and the needle had not moved off "Full". I'd normally be getting close to needing more by then.. So to be safe, I bought a box of Blue DEF and put it in.. well most of it... I got 90% of the box in before it was full.. At that point I knew my gauge was busted but in the last 500 miles its started working again. Normally I just wait until I'm about 1/4 full and throw a box in.. that seems to be perfect... Maybe it was coincidence but I don't think I'm going to use a pump again.

 

[MMothersell]

DEF consumption will vary depending on driving habits etc. You should alway just keep it between 1/4 & 3/4 full. Especially in the winter, as it is mainly distilled water and will expand when it freezes. Your guage may not have moved if the outside temperatures were below freezing and you didn't drive it enough for the DEF Heater to thaw it out. Also don't waste your money on Blue Def, Walmart brand DEF is just as good and half the price. DEF is DEF. No difference from one brand to another.

 

[stevenP]

Never heard of an over fill issue before. On my 14 the manual states, when the needle gets to 1/4 full..... in the red...2.5 gallons will fill it. Always used the walmart DEF as well with no issues. My truck is used to tow a large fifth wheel, and it uses DEF at a far rate. When not towing it lasts all year.

I agree with firebird, the error you had may have been for expired DEF. It generally only has a shelf life of a year. Dealer may have pumped your tank and replenished with new..

 

[Firebird]

Never had an over fill issue with any of my DEF trucks, if it happens again, I would have the dealer dig deeper. Also, since it is a 2019, what is the build date? That DEF fluid could have been in the tank for a long time, it does have a shelf life.

 

[BWL]

In the winter it's best to keep it below 3/4 because it can freeze and split the tank. Also, the def pump keeps running to purge the lines after shut down so it needs space in the tank for that fluid to drain or the pump and lines may be damaged and it's also quicker to thaw if there isn't as much def in the tank. If it's not freezing then overfilling shouldn't be something to worry about. Also if you fill it till it overflows the guage probably will not move for quite a while. The stations that have def pumps always seem to be out around me so I'd say the stuff is fresh when they have it. It does have a shelf life and will crystalize if it sits a long time, which can mess with the sensors. Also, the pumps don't like cold weather much. Every winter I desl with constant dead trucks and machines with def related problems, but now we don't fill them past 80% in the winter and put heat pads on the tanks that we plug in with the block heaters and that's cut down the number of break downs considerably.

 

[Aharleyguy]

Ok, I have seen some post where guys are just using distilled water in the def tanks. Does anyone know if that really works? ?
By the way may gauge is struck just above the red zone and will not move to full . . ? Any thoughts about that ?

 

[WY-Dave]

In the 4th gens, the DEF tanks is 5.5gal. The Wally DEF (been using since after the first box of blue) is what I use. When the tank reads with the needle just below 50%, I throw in a 2.5 gal jug. This gives about .5gal for expansion. Going on 3rd winter and no issues.