DEF usage, filling
Posting Guru
Joined: Oct 2010
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The sensors in the DEF tank are similar to the sensors in RV water storage tanks (e.g, full, medium, almost empty) as Crazy posted above. They cannot be float gauges due to the possibility of the DEF freezing. That would wreak havoc on such a gauge. The problem with incomplete fill-ups is that if the added DEF doesn't reach at least the middle sensor, the truck's computer doesn't know that any DEF was added at all and will assume it has been used up when there is really a gallon or two in the tank.
The best thing to do is to simply fill it when a person gets the 800 mile warning. Throw two boxes or 5 gallons in and the high sensor will register and start the process over from the beginning. If you can't fill it, you have to get at least enough in the tank to reach the middle sensor.
The best thing to do is to simply fill it when a person gets the 800 mile warning. Throw two boxes or 5 gallons in and the high sensor will register and start the process over from the beginning. If you can't fill it, you have to get at least enough in the tank to reach the middle sensor.
Post Fiend
Joined: Apr 2004
Posts: 5,158
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From: North of Salt Lake City
The reason I asked, was that I know I was somewhere in between the "less than 1/2" but more than the "800 miles" message when I topped it off last night. I put in a full 2.5 gallons and about half of the second container. Curious if I added less than the 3.5 gallons that PowerStrokeHD mentioned, will I still get the 800 mile message?
Posting Guru
Joined: Oct 2010
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Yep, topped it off. PowerStrokeHD mentioned a minimum required add of 3.5 gallons (made it sound like you needed to add a minimum of that amount to get it to reset).
Post Fiend
Joined: Jan 2009
Posts: 6,521
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From: Greenwood, SC
I have tried to get folks to treat the system in this manner for months. I do the same thing, it's easy, clean, and worry free. 'cept I run it down to 100 miles just to be sure that I don't have any left over in the second 2.5 jug.
Lead Driver
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