Hi All,

In the middle of a honking road trip with our 2018 F350 6.7 towing our 11k Fiver. About 300mi outside of Flagstaff, AZ, we got the 500mi DEF caution and the tank was around 1/3 full.

Once we got to Flagstaff, with about 1/4 DEF tank and 200mi or so until empty per the DEF status, I added 5 gallons of Peak Blue DEF.

The DEF tank shows full, however, it still thinks its low and is now showing 90mi until speed is reduced to 50mph. I spoke with the local dealer, and they say it will go all the way down to 0, and then reset. However, based on the constant message stream saying to add fluid, I'm not sure that is going to be true.

Has anyone dealt with a similar issue? I plan on grabbing another jug of DEF to top it off, but I was hoping it would clear with the 5 gallon add.

Thanks!

 

I'm not sure about the 2018 but i bought my 2017 brand new, actually ordered it custom built from dealership. As soon as i got it I went on a road trip from washington state to Mississippi, I got to about half a tank of DEF before i topped off, it reset the gauge just like a fuel tank gauge. only issue i had was driving from washington to MI was i got a check engine light which turned out to be a O2 censor which was caused by altitude change, took a day for computer to adjust itself and all was fine afterward.. only mentioned that as you said you where on a road trip. You might wanna get a 2nd opinion at another dealer or call your dealer you purchased from, from my experience they are more likely to help you than a random dealership...

 

You have to fill it all the way to the top for it to reset

 

 

mine has always reset sometimes after restarting it a few times and only putting in 2.5 gallons not all the way full that is scarry NOT GOOD MY FRIE3ND

 

Hmm...sounds odd for sure. As mentioned above, mine operates just like a fuel gauge. I've hit the low warning a few times, but adding just one jug brought me to just over half and the warning went away.

 

i have a 2017 and i have gotten that message before all i do is buy one jug and put it in and the message goes away as soon as i start the truck up. im not sure whats different (if any) on a 2018

 

You could possibly have a bad/faulty sensor

 

I think the sensor is bad.

While on my first long road trip I put a single jug of def in mine when it got to 1/4 tank. It was up to 3/4 a few minutes later.

 

 

Update: All is good!

After the truck sat for about 2hrs while at dinner, it fired up and the message was gone. Guessing it just needed a little time to register.

FWIW, I grabbed a couple more jugs of DEF today and was able to add another gallon or so before it didn't take any more (using the Ford DEF nozzle).

In the future, I am just going to plan on filling it up before it trips the 500mi warning.
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Thanks y'all for the help!

 

Glad it finally reset for you. This is a known (albeit rare) issue that Ford has no cure for to date. Mine has had it since day one. The cure for me is to never let it get to the 500 mile countdown. When it gets below 1/2 tank, I refill and haven't had an issue since. It certainly is an unnerving feeling with a big 5ver in tow watching the threat to limit you to 50mph pop up every ten miles or so. I had it happen to me on the way home from IN to MA the first time. (An 800 mile trip.) Filled when it was at 475 miles or so and it didn't reset for the full 500 miles. I was at 0 miles until reduced speed for the last 25 miles or so. Once it hit 0 miles, the message changed to telling me I'd be limited to 50MPH at my next start up. Well, didn't it reset as I backed down my driveway. So, on my truck the 500 mile warning takes almost exactly 500 miles to reset after refilling... and Ford has no way to fix it. The second time it happened on the way home from FL, I took pictures along the way showing a full DEF gauge and the countdown running hundreds of miles later as shown on my odometer and the countdown on the center screen. The best I got was that they were working on it... If ever anyone is caught by this bug and you can get to a Ford dealer, they can reset your countdown timer with IDS. Very inconvenient in the two situations it happened to me due to the RV and time of day but if your stuck, it can be forced to reset at the dealer... after ruining your day. This is why I opted to just refill well before 1/4 tank / 500 miles to reduced speed.

 

No you don't.

 

The 11-16's were fussier with their 3 probe system and some had issues with a partial fill. The 17+ trucks have a new sonar (for lack of better term) system that shoots the signal up from the bottom to check level. What I find strange is that the gauge will show full within a couple miles of filling up but the countdown to 50MPH never resets. You'd think the two systems would get their info from the same feed but apparently they are independent.

 

Glad to hear your issue was resolved - I think I'm going to fill up my DEF tank today just to be on the safe side. Since this is the first time filling can anyone tell me how to know when the tank is full? (sorry to hijack the thread!)