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Started the truck today and got the 46 miles to 50 mph max warning. Plenty of Def in tank - says 1700 miles.
Nearest dealer is up in Homestead Florida. Until Monday morning does anyone have any suggestions as to what I may be able to do in mean time.
TIA
did you just add the def after you got the def warning?
not sure if def warning is a pending code or perm code......pending codes can be cleared using a tool...perm codes have to be cleared by the pcm once the pcm verifies the condition no longer exists.
did you just add the def after you got the def warning?
not sure if def warning is a pending code or perm code......pending codes can be cleared using a tool...perm codes have to be cleared by the pcm once the pcm verifies the condition no longer exists.
No, I filled up with the def that is in the tank at Buc-ee’s up in Georgia on the way down back in December.
I got the 500 mile warning once when the tank was still 2/3 full. Refilled the tank anyway, and after two restarts the warning went away. Worth a shot.
Does your 2021 truck have any emissions warranty left? If not, how fast can you get your hands on an emissions off tune?
I got the 500 mile warning once when the tank was still 2/3 full. Refilled the tank anyway, and after two restarts the warning went away. Worth a shot.
Does your 2021 truck have any emissions warranty left? If not, how fast can you get your hands on an emissions off tune?
Out of original OEM warranty as truck has ~40k on it now. That being said I do have an ESP.
The emission off tune is something I am not familiar with but interested in.
I believe that your emissions warranty is 5yr/50,000 miles.
I think you are correct, however I believe I bought the truck 4/2/21. I think I am good with the ESP. If not I am at the mercy of the dealer. Lol
It’s all good. I planned getting an early departure for my trip up north but that looks like I may need to delay that. Just hoping the local dealer sells/services a lot of diesels and gets it right first time.
I got the 500 mile warning once when the tank was still 2/3 full. Refilled the tank anyway, and after two restarts the warning went away. Worth a shot.
Does your 2021 truck have any emissions warranty left? If not, how fast can you get your hands on an emissions off tune?
Bravo, bingo. Drive to Advanced Auto Part Store and bought gallon and a half to top off the tank. Initially I restarted the truck several times with no difference. Still had the warning about derating now in 44 miles. Went back up to front of store to throw out the packaging from def purchase and went inside to ask if they accepted used oil since I will hopefully be doing an oil change before I leave. Went back out started truck and got back on main road and after an 1/8 mile after merging in noticed the symbol for the chicklet indicating the def issue was no longer in the bottom of the display. Still have CEL but after a few more tries of starting it no longer gives me the warning for derate or chicklet symbol in the display.
so thanks to all and crossing me digits.
edit to add:
think I am going to drive this truck more when I am down here as I typically only use it to launch the boat and retrieve it through out my stay - which is very infrequent. Maintenance and pulling the boat if long stretches of windy days sometimes a week or more to keep the bottom clean since the running surface is still original gel coat. With my wife’s Bronco down here I probably only put less than 25 miles in the truck in 5 months.
You Alumina Duty guys have the bigger tank, 7.5 gal, IIRC.
My old girl has the 5 gallon tank...
Recently had got the 500 mile warning myself and let it go for awhile. When got down to 99 miles, which obviously is an estimate by the PCM, this popped up.
Never saw this because I never let it get this low before. Then the message popped up for every 4 mile reduction.
Put in about 3 gallons, all I had left at home, started the truck, the warning and the DEF "chicklet" symbol was gone.
I have also added DEF during the winter time but not filled up due to it freezing and not had any issues as well. I replaced my DEF pump and heater/sending unit in my driveway last year. Not an easy job but doable...
It will be nice to get this programmed out of the PCM once Ford and even the aftermarket tuning guys move forward with this due to the recent ruling from the EPA.
Last edited by Overkill2; Apr 5, 2026 at 08:14 AM.
Reason: Add to post
I was getting that annoying warning every 4 miles as well. Looking forward to when those programming changes become available. This was potentially be an issue being this far from home and no local familiar Ford dealer.
Also I am slated to leave in the 9nth. Just too much to do to pack up everything. I just finished repacking all 4 bearing/race sets on the boat trailer to insure no issues getting back up north. Dunking those axles in salt water can do some nasty stuff to those bearing even with the best of seals.
I was getting that annoying warning every 4 miles as well. Looking forward to when those programming changes become available. This was potentially be an issue being this far from home and no local familiar Ford dealer.
Also I am slated to leave in the 9nth. Just too much to do to pack up everything. I just finished repacking all 4 bearing/race sets on the boat trailer to insure no issues getting back up north. Dunking those axles in salt water can do some nasty stuff to those bearing even with the best of seals.
Oh yeah... I'm sure ocean water does things to bearings like the salt/spray does to vehicles here if not maintained...
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