Adding Def Doesn’t Move the Guage
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Mountain Pass
Joined: Oct 2020
Posts: 107
Likes: 5
From: Dothan, AL
Adding Def Doesn’t Move the Guage
I’m pulling a 10k TT on a 3k mi trip. When I started the def tank was full and I needed nothing for the first 1k miles. I then received the warning at 500 miles left. So I added 2.5 gal (all they had at the fuel stop). It didn’t stop the warning. Put another 2 gal in later. The gauge now reads over half full but the warning stayed on that I had less than 500 mi to go. After driving locally without the TT for about 100 mi, it now reads that I have about 900 mi left. I realize that towing probably uses more def because of the load (like the fuel economy), but it used to show 7k miles on a full tank of def when not towing. Either the gauge is undependable or I’m sucking def out the tailpipe like crazy. 2/3 full should get more than 900mi, right?
Super Moderator
Joined: Aug 2008
Posts: 37,384
Likes: 1,868
From: Frederick, MD
There is no problem here.
Towing uses more def than not towing.
Towing is less regens vs non towing.
Your system is confused because imho, you should have let the def get down to less than 200 to empty and then do a complete refill. Going down to less than 200 and then doing a complete refill will reset the system and does not confuse it.
So the guage is fine, just understand that it is a constant calulation based upon use. I get 3K on my def (2021 F450) due to towing heavy.
Not towing would probably be around 5K.
Towing uses more def than not towing.
Towing is less regens vs non towing.
Your system is confused because imho, you should have let the def get down to less than 200 to empty and then do a complete refill. Going down to less than 200 and then doing a complete refill will reset the system and does not confuse it.
So the guage is fine, just understand that it is a constant calulation based upon use. I get 3K on my def (2021 F450) due to towing heavy.
Not towing would probably be around 5K.
New User
Joined: May 2021
Posts: 21
Likes: 2
I’ve also found the gauge on my 2019 is a bit off. I took it down to about 90 miles remaining and put 5 gallons in, it took it up to the full line. Operators manual shows it takes 7.5 gallons. Towed another 1k miles and I’m below half. Got it, burn more towing. But shouldn’t have gone from E to F with only 2/3 the listed capacity. May be a similar case for you. Thought it was full but then realized it wasn’t and readjusted
Thread Starter
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Mountain Pass
Joined: Oct 2020
Posts: 107
Likes: 5
From: Dothan, AL
Thanks for the replies. Senix that sounds reasonable. My concern is the warning, knowing that if I get down to 50 miles (I think that’s the figure) the power will begin to decrease (or some such gov’t imposed eco- punishment). I usually carry a 2.5 gal blue with me, but I had used it up. Anyway thanks for the help. I’ll try the 200 mile experiment.
Super Moderator
Joined: Aug 2008
Posts: 37,384
Likes: 1,868
From: Frederick, MD
If traveling, there are plenty of Walmarts and truck stops that sell def. So don't be afraid to not have any onboard if you are running with just the truck.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
New User
Joined: May 2021
Posts: 21
Likes: 2
If traveling, there are plenty of Walmarts and truck stops that sell def. So don't be afraid to not have any onboard if you are running with just the truck.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
Hotshot
Joined: Dec 2005
Posts: 10,256
Likes: 7,694
From: Chino Valley, Arizona
Not to get too far off topic, but is anyone aware if the nozzle on the DEF pump at truck stops will fit our tank? It’s a small opening so I doubt it, but I typically see it for $3 a gallon which is far cheaper than the $20 a box I’m used to seeing. I haven’t driven up and checked myself, just curious if someone on here may have.
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Junior User
Joined: Dec 2020
Posts: 76
Likes: 23
If traveling, there are plenty of Walmarts and truck stops that sell def. So don't be afraid to not have any onboard if you are running with just the truck.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
I usually will carry enough for a complete fill I towing and then when used, Walmart will be a stop for re-supply.
Also my best advice is the purchase the ford filler spout. It will fit the all the containers. It seals to prevent leaks when filling and won't allow an overfill. Important in the winter to not be over full. DEF freezes and would crack the def tank.
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Cargo Master
Joined: Feb 2015
Posts: 2,338
Likes: 255
From: Livermore Ca.
Just go to the dealer they should have them in stock. They are about $10 I think. Money well spent.
Cargo Master
Joined: Feb 2015
Posts: 2,338
Likes: 255
From: Livermore Ca.
If you want to keep your DEF system happy don't keep topping it off every time you stop for fuel. That is what keeps the system wondering why the truck isn't using any DEF. BUT your truck shouldn't regen much more than every 500 miles. No way should you use a gallon with every regen. If you are then you need to hit the dealer to find out why.
Thread Starter
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Mountain Pass
Joined: Oct 2020
Posts: 107
Likes: 5
From: Dothan, AL
Thanks all. I went to a truck stop on the last fillup. They had a very convenient def filler. (Also free tire air). I topped off the def - only took about a gallon and a half. And, wahlah the mileage estimate jumped up from 900 to 2500 miles before def fill. This is during towing a 10k TT. In the future I won’t be quite so panicky about low def, and I’ll top of completely if possible.
This is totally off topic but after the last stop, I am unable to select drive modes (including tow mode). I get the idiot light that tells me that. I still have about 500 mi left on this trip. What’s that about?
This is totally off topic but after the last stop, I am unable to select drive modes (including tow mode). I get the idiot light that tells me that. I still have about 500 mi left on this trip. What’s that about?
Prolocutor
Joined: Jan 2009
Posts: 13,618
Likes: 1,247
From: Western MA
I'm late to the party here but my truck has the same issue and Ford has no fix. It will not reset for quite a while after refilling. I too have had the fear of being stranded as it counted down from 500 to 300 to 200. When it gets to 50, the panic really sets in... (Especially if you have a 44' 20,000lb RV behind you, in the pouring rain, in the dark, with your family onboard, on a busy highway...) Luckily the only time it did that, I was almost home. Let the truck sit overnight and it finally reset. This has happened to me quite a few times and each time, no matter how low it is when I refill, it doesn't reset until being shut down for a significant amount of time like overnight. It also doesn't matter if you partially refill it or completely refill it. I've taken to never letting it get below the 1/2 way mark and that has cured the issue. If it can't get into countdown mode, it can't need to be reset.
Mountain Pass
Joined: Jul 2019
Posts: 175
Likes: 7
From: NW Suburban Chicago
