DEF always reading as Low

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Dec 23, 2023 | 09:13 AM

lsypeck

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DEF always reading as Low

My 2012 Ford F-450 (300K miles give or take) always reads that it has low DEF but is full and runs fine. Is there anything I should worry about?

Dec 23, 2023 | 10:30 AM

FishOnOne

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From: The Great State of Texas

If it were me I would just run it that way and top it off with DEF at each oil change.

Dec 23, 2023 | 12:16 PM

Overkill2

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From: Western NY

I don't think the first gen design of the DEF tank level gauge is really accurate but you could have an issue with it, but as long as there's no CEL and you keep it full, and as long as the truck doesn't go into the "500 miles until empty" mode, which at the end of the 500 miles, would cause a engine derate, I'd say you're probably fine.

Dec 23, 2023 | 04:07 PM

The Bone

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From: Livermore Ca.

He may want to let the truck go until the 5t00 miles thing then fill it up. Maybe that would fix the sensors. Folks that keep it topped off are the ones having issues.

Dec 23, 2023 | 05:13 PM

Overkill2

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From: Western NY

Quote:

Originally Posted by The Bone

He may want to let the truck go until the 5t00 miles thing then fill it up. Maybe that would fix the sensors. Folks that keep it topped off are the ones having issues.

I'm one of the exceptions to the rule Bone. I never had a problem adding DEF before it went down to the 500 mile warning. With that said, I did fill it this last time when it got down to the warning.

Dec 23, 2023 | 06:21 PM

FishOnOne

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From: The Great State of Texas

Quote:

Originally Posted by Overkill2

I'm one of the exceptions to the rule Bone. I never had a problem adding DEF before it went down to the 500 mile warning. With that said, I did fill it this last time when it got down to the warning.

Add me to that exception as well. I think I let it go down to 500 miles one time. All other times DEF was less than half full when I topped it off

Dec 23, 2023 | 07:04 PM

senix

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From: Frederick, MD

I would suggest running it down to <200 miles to empty, then a complete fill.

Running it down may allow the system to reset. As of right now due to the sensors in the tank it is confused.

I have always let it run down and then do a complete fill.