Infinite DEF
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5th Gear
Joined: Mar 2024
Posts: 5
Likes: 1
Infinite DEF
Figured that title would turn some heads, Lol 2023 F-350 12,000 miles. On start up gauge reads 5% then slowly climbs to 91%. Anybody ever heard of this? Some would say its a blessing but that filter is gonna get clogged at some point and shut me down, probably in downtown atlanta while im pulling a #20k camper. Thanks in advanced.
Lead Driver
Joined: Dec 2020
Posts: 8,634
Likes: 2,429
Sounds like you are talking about DPF%, not DEF level. The DPF% should climb until full, or near full, regen starts, burns it down, and the cycle repeats. If it is in fact the DEF level you are looking at, I'm not sure how it could lead to clogging of the DPF, but what you describe would be unusual.
Lead Driver
Joined: Nov 2005
Posts: 8,453
Likes: 4,952
Figured that title would turn some heads, Lol 2023 F-350 12,000 miles. On start up gauge reads 5% then slowly climbs to 91%. Anybody ever heard of this? Some would say its a blessing but that filter is gonna get clogged at some point and shut me down, probably in downtown atlanta while im pulling a #20k camper. Thanks in advanced.
Sounds like you are talking about DPF%, not DEF level. The DPF% should climb until full, or near full, regen starts, burns it down, and the cycle repeats. If it is in fact the DEF level you are looking at, I'm not sure how it could lead to clogging of the DPF, but what you describe would be unusual.
DEF has nothing to do with any filter, like the diesel particulate filter (DPF).
Lead Driver
Joined: Dec 2020
Posts: 8,634
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I haven't seen anything like this posted before. Sounds like a dealer visit is in order. Obviously you have added DEF over the coarse of that 12k miles.
Laughing Gas
Joined: Apr 2023
Posts: 904
Likes: 1,820
From: SE PA
I see this all the time. The tank level is measured by an ultrasonic transducer in the DEF tank and it takes a little bit of time to read the level correctly. It is working correctly.
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Lead Driver
Joined: Dec 2020
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So if that is working correctly, as you say, then the truck in post #2 is not working correctly?
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Hotshot
Joined: Oct 2015
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From: Wyoming
I have the DPF % screen on most of the time, so I don't watch the DEF screen too often. On my 2017, the DEF screens don't display a percentage as I recall. It's an empty to full gauge on one screen and and "OK" on the other screen. Is that different with the 2023?
Lead Driver
Joined: Dec 2020
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Yeah, I don't know what year it was introduced but the 23+ do have a DEF% gauge in addition to a DTE I believe.
Hotshot
Joined: Oct 2015
Posts: 19,686
Likes: 12,808
From: Wyoming
To avoid the issue of the system/sensor not recognizing the addition of DEF when the level is low and existential warnings are being displayed, I add a 2.5 gallon when the gauge goes just below half. Never had a problem with that approach.
Laughing Gas
Joined: Apr 2023
Posts: 904
Likes: 1,820
From: SE PA
If post # 2 truly checks at startup and it reads like he says I would be suspect. The DEF% display appears to have a calibration algorithm that incorporates measurement filtering like a Kalman filter, where an initial DEF% value (0) is assumed then a measurement is taken the DEF% calculated and a margin of error calculated and if the margin of error is greater than some value that the designer has specified a new value for DEF% from the measurement is assumed truth and the process is repeated updating the DEF% until the margin of error desired is achieved.
Fleet Mechanic
Joined: Dec 2012
Posts: 1,563
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From: DFW
If post # 2 truly checks at startup and it reads like he says I would be suspect. The DEF% display appears to have a calibration algorithm that incorporates measurement filtering like a Kalman filter, where an initial DEF% value (0) is assumed then a measurement is taken the DEF% calculated and a margin of error calculated and if the margin of error is greater than some value that the designer has specified a new value for DEF% from the measurement is assumed truth and the process is repeated updating the DEF% until the margin of error desired is achieved.
Thread Starter
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5th Gear
Joined: Mar 2024
Posts: 5
Likes: 1
Oh yea. She drinks the **** out of it when pulling a heavy load. From what ive read all 23 models are doing this.