Fault Code Lookup › Powertrain codes › P21B0
P21B0 Powertrain · generic range, no listed definition
P21B0 fault code: what 3 Ford owners reported
P21B0 sits in the generic powertrain range (engine, transmission, fuel and emissions), but its SAE definition is not in CarHooq's list, so this page shows only what owners reported. What it meant in practice is below, from 3 complaints owners filed with NHTSA. Updated November 9, 2026.
- 3owner reports
- 1car model
- 0mention a crash
- 0mention a fire
- 2014–2016model years
Which cars get code P21B0?
Every model whose owners mentioned P21B0 in a complaint, most reports first. Each year opens that car's full problem report. Popular models collect more reports because more of them are on the road.
Where does P21B0 show up?
By brand
- Ford3
Component the owner filed it under
Is there a recall for P21B0?
As of November 9, 2026, no NHTSA recall on the cars reporting P21B0 names this code or its most-reported component. Recalls can be issued at any time: check your VIN at nhtsa.gov/recalls.
What happened when owners saw P21B0?
3 of the 3 reports, spread across the models above, as the owners wrote them. NHTSA removes names and VINs; long reports are trimmed. CarHooq has not verified individual claims.
The recall that expired July 31, 2022 was to fix the reductant heater and sender assembly. I've had this issue ever since I owned this vehicle, but it only occurs when the DEF tank is at half-volume. Once it's at half volume, it generates the DTC P21B0 and doesn't tell me how many miles I have left in my DEF tank nor does it state how full it is. This is a risk in driving, as I have no idea how much fluid is left in my DEF tank. I was in the dealership in June to get two separate recalls resolved (21E01 as well as 21M01), but for 21M01, you needed to have the DTC present to be eligible. Well, the particular issue, 21M01, only occurs in my 2014 F-250 6.7L when the DEF tank gets near 1/2 full…
Diagnostic Trouble Code P21B0 Reductant level sensor C circuit high I know several people that have had this same issue concerning the DEF tank assembly costing close to $1000. A recall was issued for earlier models but doesnt cover my truck that now has this same issue. It's this type of failure that makes owners of diesel vehicles contemplate deleting these pollution reducing systems. Please consider an expanded recall.
I WAS HEADING FROM CIBOLO, TX TO KINGSVILLE, TX. (DISTANCE 181 MILES) UPON ARRIVING AT DESTINATION I SHUT DOWN MY TRUCK. AFTER APPROXIMATELY ONE HOUR, I STARTED MY TRUCK AND THE CHECK ENGINE LIGHT CAME ON. I CONNECTED MY OBD READER AND IT IDENTIFIED THE FAULT CODE P21B0 (I DID NOT CLEAR ANY CODES). FROM MY RESEARCH IT RELATES TO THE 'REDUCTANT LEVEL SENSOR 'C' CIRCUIT HIGH'. AFTER RESEARCHING MORE INFORMATION I STARTED LOOKING THROUGH THE INFORMATION CENTER UNDER THE VEHICLE SETTING AND NOTICED THE DEF LEVEL WAS BELOW HALF (I NEVER GOT A POP UP OR NOTIFICATION FROM THE INFORMATION CLUSTER). IN THE PAST THE INFORMATION CLUSTER WOULD DISPLAY THE LEVEL NOTIFICATION WITHOUT AN ENGINE LIGHT…
P21B0: questions drivers ask
What does code P21B0 mean?
P21B0 sits in the generic powertrain range (engine, transmission, fuel and emissions), but its SAE definition is not in CarHooq's list, so CarHooq shows only what owners reported. 3 owners reported it to NHTSA, most often for the Ford F-250 (3); their reports describe what happened.
Which cars get code P21B0 most often?
In NHTSA owner complaints, P21B0 is mentioned most for the Ford F-250 (3), across 1 model and model years 2014 to 2016. Popular models collect more reports because more of them are on the road.
Is there a recall for code P21B0?
As of November 2026, no NHTSA recall on the cars reporting P21B0 names this code or its most-reported component. Recalls can be issued at any time, so check your VIN at nhtsa.gov/recalls.
What should I do if my car shows P21B0?
Write down when the code appeared and what the car did (warning lights, loss of power, noises, speed, weather). Check your VIN for open recalls at nhtsa.gov/recalls, ask a dealer or independent workshop to read the stored freeze-frame data before anyone clears the code, and keep the repair order. If the car loses power in traffic, stop driving it. CarHooq does not diagnose: these are owner reports and official recall notices, not repair advice.
How this page was made
CarHooq read the text of every owner complaint filed with NHTSA for 19 US and European brands (model years 2012 onwards) and picked out the diagnostic trouble codes owners wrote down. This page lists every mention of P21B0. The code is in a generic range but its standard definition is not in CarHooq's list, so CarHooq shows only what owners reported. Nothing here is a diagnosis. More answers: the fault code FAQ. Data: NHTSA Office of Defects Investigation (public domain), retrieved November 9, 2026. How CarHooq reports are made.
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