DEF Level Sense Stays at full
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DEF Level Sense Stays at full
I own a 2019 F350 that suddenly showed the DEF was full when I knew it had only a half tank the day before. Took her in under warranty and she spent a week at the dealership trying to diagnose the problem. They tried multiple things like changing out the level sensor, etc. When that did not work, Ford was contacted and the dealer did several checks on the system, including wiring. They ended up changing out the entire tank and the level sense was supposedly correct after this, but here I am three weeks after this "fix," about 1200 miles, and the DEF level still shows full. Coincidentally, or not, the real reason I brought the truck in was that my EGT temp sens No. 1 had a fault. They found that a rat had chewed through the wire, but emphatically said there was no wire damage to the DEF tank level wiring. Wondering if anyone else has experienced this reading of full when not, or have any ideas? Heading back into the dealer with her next week, but I've always found there's no one more interested in figuring out my issues than your's truly.
Prolocutor
Joined: Jan 2009
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From: Western MA
If the dealer filled the tank to the top after the tank replacement and you've been driving light without towing heavy in the 1200 miles that have since passed, your tank could correctly be reading full.
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Yes, they started with a new tank and filled it. I've driven somewhere between 1200 and 1350 miles.
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I can hope so, that is for certain. I don't want to put any DEF in it to test it as the dealer did not believe me when I first brought the truck in (no error codes}, until I insisted that they try to to fill it themselves and it took 2.5 gallons. They went right to work trouble shooting it after that. I have a dear friend that was the assistant service manager, so I know I was being treated right and they did indeed struggle to find the root cause. I also know they had no idea why replacing the entire tank and sensor system fixed it when replacing only the sensor system did not.
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I am going to drive it for another thousand miles, or 2000 total since the dealer "fixed" it, to see if it registers any use. If it doesn't back into the dealer she will go. Personally, I expect the level sensor to work on an $80,000 truck less than a year old.
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Joined: Mar 2005
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From: West Michigan
level sensor is not like a fuel gauge. When not towing, takes 3-4000 miles to drop under half. Until then, nothing changes.
Cargo Master
Joined: Feb 2015
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From: Livermore Ca.
I can't remember the last time I added DEF to my truck. I don't even pay attention to it anymore. Like others do I just wait till the 500 till limp mode and then I fill it. When I first got the truck DEF drove me crazy worrying about running out. I would get a box when it was below 1/2 but it wouldn't even take a whole box. What do you do with a quart of DEF? Finely one time I got the message while in upper Michigan and freaked out. I add 2 boxes of DEF and the 500 till empty didn't go away. I disconnected both batteries and it still didn't go away. Finely after 300 miles the message went away. Sigh of relief. You don't want limp mode with a 35' 5th wheel on the back. After that experience I stopped worrying about DEF. I don't look at the gauge because it is as accurate as the black tank level in my RV.
I wonder if OP would have kept driving and the truck wouldn't realized that he didn't have any DEF in the tank and the truck would self delete. LOL
I wonder if OP would have kept driving and the truck wouldn't realized that he didn't have any DEF in the tank and the truck would self delete. LOL
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Thanks for the info! I had read that there is not simple level sensor, say like a float sensor in a fuel tank. It has some sort of system built into the heater tube as I understand it? I know you can screw it all up if you don't fill it completely when adding DEF.
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From: Western MA
There are two different 6.7 level monitors.
In the 2011-2016, yes, it's possible to throw the system off by not letting it get low enough and then doing a complete refill. There are 3 probes in the tank much like an RV holding tank. So really, you're getting an indication when you drop below each probe, not a true tank level. Now, if you keep topping it off, it is possible that the truck will get "confused" and think it's not using any DEF and send you into limp mode requiring a dealer visit to reinitiate the system and clear the issue. This happens because the upper probe is consistently submerged. If it never achieves a drop below the top probe, it will assume like I said above, that there is an emissions fault with no DEF being used.
However, from 2017 going forward, that system is no longer in use. There is now a single sonar type device at the bottom of the tank that sends an occasional pulse up through the DEF to measure how much is in the tank. This newer system is not only a bit more accurate but it also can't suffer from being too full for too long causing a dealer visit to correct.
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There are two different 6.7 level monitors.
In the 2011-2016, yes, it's possible to throw the system off by not letting it get low enough and then doing a complete refill. There are 3 probes in the tank much like an RV holding tank. So really, you're getting an indication when you drop below each probe, not a true tank level. Now, if you keep topping it off, it is possible that the truck will get "confused" and think it's not using any DEF and send you into limp mode requiring a dealer visit to reinitiate the system and clear the issue. This happens because the upper probe is consistently submerged. If it never achieves a drop below the top probe, it will assume like I said above, that there is an emissions fault with no DEF being used.
However, from 2017 going forward, that system is no longer in use. There is now a single sonar type device at the bottom of the tank that sends an occasional pulse up through the DEF to measure how much is in the tank. This newer system is not only a bit more accurate but it also can't suffer from being too full for too long causing a dealer visit to correct.
In the 2011-2016, yes, it's possible to throw the system off by not letting it get low enough and then doing a complete refill. There are 3 probes in the tank much like an RV holding tank. So really, you're getting an indication when you drop below each probe, not a true tank level. Now, if you keep topping it off, it is possible that the truck will get "confused" and think it's not using any DEF and send you into limp mode requiring a dealer visit to reinitiate the system and clear the issue. This happens because the upper probe is consistently submerged. If it never achieves a drop below the top probe, it will assume like I said above, that there is an emissions fault with no DEF being used.
However, from 2017 going forward, that system is no longer in use. There is now a single sonar type device at the bottom of the tank that sends an occasional pulse up through the DEF to measure how much is in the tank. This newer system is not only a bit more accurate but it also can't suffer from being too full for too long causing a dealer visit to correct.