DEF Guage Stuck.

[tmcgraw]

Hi all. I filled my DEF tank in my 2018 RAM 3500 on a trip last October. Unfortunately, the guage on the dash continues to show the DEF tank as full. I carry DEF fluid and after a few diesell fill ups I top the tank off. Bit of a pain. Any suggestions on how to free the guage, short of taking it in to the dealer and gettiong overcharged? Thanks Tom

 

[chopperman1]

It's not stuck, you simply haven't used enough to change the level. You use approximately 1 gal of DEF per 1000 miles (unless towing heavy). When you "fill" the def tank, you actually overfill it. Best to run it down to a 1/4 then add 1 container. This allows you to keep fresh def in the tank and the fluid movement in the DEF tank will keep it clean from crystallization.

 

[nlambert182]

Mark the mileage when you top off the DEF tank. Ignore the gauge for the next 5k-10k miles and DON'T add any DEF. Willing to bet it will move. chopperman is right... if you're empty you're not using much at all. Hook up to something heavy and take a 1k mile trip and you will see it start dropping.

I only had to add DEF twice per year in all of my 2500/3500s and I average about 15k-20k a year with about 1/3 of that towing heavy. If you're not getting any EVIC messages, stop topping it off and leave it be.

 

[poopsleeve]

Your DEF Guage is part of your pump. Mine quit working. Drove it for year like that. Guessing when i need a fill up.
When i got sick of it , I bought a new pump. Problem solved in my driveway for a grand.
Helpful info : you can save yourself some swearing by purchasing the spanner wrench required to loosen the access door. You can do it without the big spanner but it's not easy.
Also remove the fill access to evacuate all the DEF in the tank first or you will get whatever is in the tank all at once and probably not enjoy it.

 

[Hudson]

Listen to everyone above. Just did it this weekend. Ran the truck to 1/4 DEF and dumped the whole 2.5 gallon container in. It took 3 starts but my DEF gauge reads FULL. See you in 5K.... I think I read somewhere that opened containers of DEF deteriorate much faster than sealed ones. I should have kept the container and left in in the driveway with a sign:

"PLEASE LEAVE A URINEA SAMPLE HERE"
"CANT AFFORD DEF FLUID"

 

[18CrewDually]

FYI: When it reads 1/2, you can fill with a box 2.5 gallons and it will take it all and actually be full.

 

[Hudson]

Does the gauge become really accurate form 1/2 to zero?

 

[18CrewDually]

Does the gauge become really accurate form 1/2 to zero?

I found it to be accurate on both sides of half. When it's real low on the gauge, 1 box of def brings it to half tank. 2 boxes bring it to full.

 

[Hudson]

I found it to be accurate on both sides of half. When it's real low on the gauge, 1 box of def brings it to half tank. 2 boxes bring it to full.

Thanks for the info.

 

[06 Dodge]

FYI: When it reads 1/2, you can fill with a box 2.5 gallons and it will take it all and actually be full.

I wait until 1/4 tank then stop by Wally World for 2.5 gallons of DEF to add to the tank

 

[WY-Dave]

The tank is 5.5 gals, a 2.5g container @ 50% will do you good. Never hurts to go blow half, but anything above, that's a different story

 

[nlambert182]

I typically wouldn't top mine off either unless I knew I was about to go on a long towing trip. That helped ensure that the DEF in the tank wouldn't sit for 6-8 months before I burned through it all. 1/2 tank is about the max I'd fill it up if I were mostly going to be driving around town and taking unloaded trips. Old DEF can crystalize on the DEF injector and clog it, and potentially clog the pump too.

 

[18CrewDually]

I typically wouldn't top mine off either unless I knew I was about to go on a long towing trip. That helped ensure that the DEF in the tank wouldn't sit for 6-8 months before I burned through it all. 1/2 tank is about the max I'd fill it up if I were mostly going to be driving around town and taking unloaded trips. Old DEF can crystalize on the DEF injector and clog it, and potentially clog the pump too.

My truck sits in the winter when the salt is out. I park it topped off fully. For DEF to crystallize it needs air, exposure. When the tank is full there is no air gap exposure eliminating the chance.
For example, it's like an old car that was parked and sat with 1/4 tank of gas. When you drain and clean the tank, the tank and sender unit will be corroded all above the gas level.

 

[nlambert182]

If DEF goes bad, it will lose some of its effectiveness and can overdose the system where it won't all be burnt off. It can cause the SCR, the injector, and the exhaust to clog.