No, it had reset on its own. They did reinitiate the system though. A fancy word for reboot I guess? It did nothing to help the issue.

 

Thank you for the education. I didn't see when scrolling where anything changed (nothing referring to a level sensor within the DEF tank section) in the 2020 update book but I now see what you're referring to explained in the reductant quality module paragraph. Is the gauge getting the data (BCM?) from from the DEF quality module?

Since the DEF tank is known full, speakerfritz needs to drive for 2,000 miles and observe the gauge results. Or we are missing important information in the first post.

 

yes drive the truck for many miles and the notification of less than 200 to empty.

 

I'm honestly not sure how it works now. I remember when Curtis (Pocket) was here he explained it in detail as it was his wheelhouse with Ford. All I remember is when the 2017 redesign came out the DEF tank got bigger and lost its side probes in exchange for the single bottom sensor. This prevented the issue the 11-16's had with frequent filling fooling the system into thinking there was a problem.

 

I have not filled DEF from a JUG in a long time. If I'm at a station that has DEF at the pump and I notice that I' Half or lower, I top off.

 

Don't know if you gone to the dealer yet but the DEF gauge is definitely not accurate at all. Anyway, I always wait to fill after gauge indicates less than 1/4, sometimes I've gone down to near zero but it will only take 5 gallons. So based on the miles I have driven before filling, you should be safe going up to 3k depending on your driving particulars. Since you use a DEF box, I would carry one starting at 2k after filling up and just wait and see if the system ever realizes your empty. This may help "clean" the sensor if its crusty. Just a thought.

 

I have a 2015 and had a problem with the Def 500 mile light coming on even when I just filled with Def. Got online and searched for several hours and came across 1 post that stated the same problem. He bought a box of premium blue at someone’s suggestion and it cleared up after about a day. Showed a picture of it actually desolving some of the crystallization . Bought a box and tried it and it solved my problem. For $30.00 worth looking at. At least it was $30.00 six months ago.

 

My 2016 has done that one time since new. I filled up with DEF at a truck island and after driving away from the pump I got the 500 miles to empty. The message went away on it's own the next day at 449 miles to empty. The OP has a different gen truck than we do with a different sensor assembly so it's not really apples to apples.

 

I've filled mine every 3k to 4k miles before with no problems. And I've let it get down also to the 500 mile limit and filled with no problems.

 

thats right, my dash def gauge always shows full so there’s no way to tell if it’s nearing empty , etc.

not having a way to know when it’s nearing empty….since it’s always shows full…I just refill it every tank full of fuel.

it takes about a gallon and a half of def per 50 gallons of fuel.

i do not know if I let it run to empty if I would get any warnings since the dash is always indicating full.

even if I wait until two or three tanks of fuel goes by…it will still show full even though I’m adding 1.5 to 3 gallons of def.

so basically it consumes def, it’s just not accurately indicating how much def is left.

 

do you think my “500” mile limit warning will come on if my def indicator always indicates full?

 

i switched to premium def to see if it makes a difference . Nothing yet. I’ve run 5 gallons of premium def thru it so far.

 

According to your estimation, you use approximately 6.0 gallons of DEF for 200 gallons of fuel. You'll have one gallon left after 200 x average MPG. If you add another 33 gallons after that, you should have a half gallon of DEF left, assuming your calculations are correct.

I would think so. Go for it and find out.

 

toss this out there
since its been an ongoing issue,
and the systems have had some issues,
have you tried to use a pump and suck out all the def and see if it sets a light or changes gauge reading?

mine stays FULL until one day after a few hundred miles it will drop to 3/4 and then hang there for long long time, at least 500 miles, then it will go between 1/2 and 3/4 and then i top it off.

i have also had to stay at full for several tanks of fuel, then one day drop to 3/4
i have also driven straight for 10 hrs, and used 700 miles of fuel at 78 mph or more and it never changed from off full.
i have also driven the same route on return and it went down to 1/2
both trips it did passive re gens and kept the dpf around 20%

then did the same trip a few months later and dpf did a commanded regen and then kept it at 20% and used 3/4 def, i filled up and drove back the next day and it stayed full.
so i think the system has no real set of rules, so many variables in the logarithm from dpf egts, road speed, fuel quality, winds, temps etc.

i would drain the def tank and see if it makes a difference in gauge reading. or drop it and really empty it and see ??

 

I tried to drain it with a 1/2 hose,,,but it wouldnt go down enough ....maybe a 1/4 inch hose ....sounds good in theory..but I dont think anyone has actually drainied the def with a hose thru the fill.

I defintely would love to drain it .