DEF Code P21B0
Thread Starter
|
Mountain Pass
Joined: Feb 2006
Posts: 105
Likes: 3
From: Gilbert, AZ
DEF Code P21B0
I get a code when my DEF tank is at about half full. Code look up indicates DEF level sensor C High, so i assume the level sensor is shot. Is this part of the Tank or the pump assembly. cant seem to find just the sensor to replace. Fortunately it doesnt shut me down, just an annoying CEL.
AZChris
AZChris
Freshman User
Joined: Aug 2011
Posts: 40
Likes: 0
Just had this problem fixed under warranty. Dealer replaced the Sensor/Heater assembly. Someone correct me if I am wrong but I believe that the DEF tank has to be removed to replace the Sensor/Heater assembly. I also heard that this is a common failure and the Ford part is backordered. My dealer got lucky in finding on the shelf at another dealer.
Post Fiend
Joined: Nov 2001
Posts: 6,748
Likes: 118
From: Tallassee, ALabama
I have not heard it being a common failure. I have read where some have a problem of the PCM/ECM registering when you fill the tank. For some, it seems to take some driving for it to reset.
Yes, on a pickup, the tank has to be dropped to change it.
Yes, on a pickup, the tank has to be dropped to change it.
Thread Starter
|
Mountain Pass
Joined: Feb 2006
Posts: 105
Likes: 3
From: Gilbert, AZ
As i live in Phoenix and we have emissions testing with inspections, not sure i can delete and not receive heavy fines. (stupid EPA and Local Env agencies)
Trending Topics
New User
Joined: Jul 2021
Posts: 5
Likes: 1
I am having the same code on my 2014 F-250. Were you able to keep driving indefinitely by just keeping the DEF topped up? With a long trip coming up, I am worried about it going into limp mode.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread Starter
|
Mountain Pass
Joined: Feb 2006
Posts: 105
Likes: 3
From: Gilbert, AZ
I replaced the assembly once. On the new one i get an occasional CEL. This time it happens after i fill it. I use Forescan (Lite) to clear the CEL. I have yet to have it go into limp mode. Keep it half to full or more and i would think you should be fine. I have a new one to replace it but just havnt had the time to do it.
Cargo Master
Joined: Feb 2015
Posts: 2,338
Likes: 255
From: Livermore Ca.
I would not say you can drive indefinitely. If the truck thinks the tank is empty than it will go into limp mode at some point. You may be able to reset the light but at some point the truck will say thats enough and limp you.
New User
Joined: Jul 2021
Posts: 5
Likes: 1
I topped off the DEF completely. Cleared the Code and it did not immediately return. The system info screen is saying that it is less than 1/2 full. My understanding is that there are 3 level sensors and the ground sensor. So as long as they all do not go bad, It seems that I can keep it out of limp mode.
Cargo Master
Joined: Feb 2015
Posts: 2,338
Likes: 255
From: Livermore Ca.
Ya that may hold but you should get this fixed as soon as you can. If the truck still works then let it use some DEF from the tank then do the repair. If it goes intom limp mode then it's a real pain to get it back. I had limp on my truck for the DEF nozzle and it toos 3 tries before he could clear the light.
5th Gear
Joined: Sep 2018
Posts: 5
Likes: 0
Just got that code on my truck. Filled it full with almost a whole cube of DEF so it was pretty low. When I was first getting the code I could not see the DEF level at all on my information screen but now that it’s filled it’s at least showing under 1/2 full. Will drive some and see if it clears. I have an appointment with the dealership next Monday will see what happens.
Last edited by droptoppop; Aug 18, 2021 at 08:32 AM.
New User
Joined: Jul 2021
Posts: 5
Likes: 1
I had the code and the option to show the DEF level did not even show up. After I topped it with DEF, it showed "Less than 1/2" for about a day. Then showed "DEF Level OK." Started out on my 3400 mile trip. I kept monitoring the DEF level display. It went from OK to throwing a code and not showing the display when it was probably about half full. Keeping it topped off with DEF resets everything and allows the truck to drive normally. There was a customer service bulletin that applied to the 11 and 12 model years of the F250 andF350 (additional years for 450 and 550.) My 2014 would not be covered when I spoke with the dealer. From what I have gathered from the forums is that a portion of the level sensor is bad. It is part of the heater assembly and can only be replaced as a unit. Has anyone had luck with a non OEM replacement? Amazon and eBay versions are about $100. Seeing as the OEM version is a known bad product, I am hesitant to re-install a unit that will likely fail again. For now, I am continuing to drive and just keeping the DEF level topped off more frequently.