Ford F150 Check Fuel Fill Inlet. Meaning & Easy Fixes!  

Your Ford F-150 check fuel fill inlet sign usually means there is a leak in the EVAP system, the fuel tank, or cap. The easiest way out is to properly seal the cap or fix the inlet pipe. Or you can also use a gas station nozzle for breaking the lid and cycling it in and out multiple times.

Now, the Ford F-150 check fuel fill inlet is a common error core, especially as Ford F-150s have a capless fuel filler system. So, don’t freak out. I will guide you to fix the code.

Common Causes and Solutions of Fuel Fill Inlet on Ford F-150

Ford’s capless fuel filler system is not so efficient as it often leads to fuel fill inlet problems. So, What problem does Ford F-150 check fuel fill inlet entails? Let’s see what these problems are and the underlying solutions. 

Evap LeakThe smell of fuelUnsecured gas capVacuum pressure leakLeak in one of the hoses or a defective O-ring seal Use EVAP smoke machine to diagnose the problem EVAP system needs to be manually vacuumed down. Use smoke to perform the same test and locate pressure restriction.
Dirt contaminationDebris or dirt on the fuel cap. Clean the mouth of the fuel fill inlet
Damaged fuel inletExcessive pressure. Long-term off-road drivingFix any rips, tears, or wear. Otherwise, replace it. 
Gas cap issuesMissing fuel capBroken fuel capBad seal of the fuel capPut the cap back onReplace the capProperly tighten the cap
Faulty sensorRandom error report when no problem.No error report when there is a problem. Fix or replace the sensor. 


Although EVAP system leaks won’t give any major trouble to your Ford F-150 you should take it seriously. The EVAP system always stops the gasoline vapors from going out into the atmosphere from the fuel tank. As a result, this problem will lead to a failed emission test.

One of the most common scenarios of an EVAP leak is at the gas station, after refueling the car. Usually, a foul smell of fuel is the first sign of a leak in your EVAP system. 


The EVAP system leakage can happen simply for an unsecured or broken gas cap. Or, if there’s a vacuum pressure leak. There might also be a leak in the connector hose or vapor hose. Or there is a defective O-ring seal. As a result, the gas leaks and the pressure increases more than the EVAP system can handle.   


To solve this issue, you can use an EVAP smoke machine to detect if there’s an EVAP leak. But first, let’s see how you can use an EVAP smoke machine to detect an EVAP leak. 

Before starting the test, inspect all of the parts of the EVAP system. If there’s no visual leak, begin your EVAP smoke machine test. Remember to always turn off the car before starting the test. 

The use of a car scanner (OBD1/OBD2) can help the test. The OBD1/OBD2 scanner will help by detecting the exact error codes that describe the problem in the EVAP. Here, if the scanner shows the P0456 code then it’s an EVAP leak. 

  1. First of all, seal the purged solenoid. It is located within the vacuum line between the intake manifold and the fuel vapor containment canister. To do this, close the purge valve first. The engine computer controls the purge valve. So, make sure it is sealed tight, and if not replace it. 
  2. Seal the gas cap.  
  3. Attach the machine to the battery of the car.
  4. Now, turn on the smoke machine. 
  5. After that, the vent solenoid needs to be closed. 
  6. See if there are any leakages in the EVAP system.

So, let’s now dive into the solution to the EVAP leak. 

Step 1: Properly close the fuel tank after refueling at the gas station. 

Step 2: If the problem is with the pressure vacuum, then manually vacuum down the EVAP system and monitor the pressure. Use the EVAP smoke machine test discussed above to manually vacuum down the EVAP system. Use a vacuum pump to remove the EVAP system’s air. 

To do this, connect the vacuum pump through a vacuum line to the EVAP system. Then turn on the vacuum pump to vacuum down the EVAP system. The FTP sensor measures the pressure in the EVAP system. The target pressure here is 8.0 in.-H2O and if it’s not met then there is a leak in the EVAP system.   

If the pressure decreases to the normal level, the warning sign will be cleared. 

Step 3: If the sign still won’t go away, there might be problems with the piping structure of the fuel tank. Seek help from a professional to diagnose and solve the issue.

Dirt Contamination

This is another common issue that results in leaks and breakages in your car’s fuel fill inlet. So, let’s see what causes this and the underlying solutions.  


Dirt contamination happens all the time if you do not clean the fuel fill inlet regularly. This problem can simply be resolved by cleaning the mouth of your truck’s fuel fill inlet. So, let’s see how to clean the fuel fill inlet.


Step 1: First, open the fuel door. Then, use compressed air which will clear any dirt and debris. 

Step 2: Inject the fuel filler funnel and then remove it. Do this 2 or 3 times.  

Step 3: Now, spray cleaning solutions(WD-40 or Seafoam, etc.) on the spring-loaded lid after closing it. 

Step 4: Use an easy fuel funnel, then cycle it in and out of the inlet to spread the cleaning solution (WD-40). 

Step 5: Keep doing this a few times (2/3). 

Step 6: Now, finish the cleaning process with compressed air. You’re good to go.  

Damaged Fuel Inlet

Now, if you have a damaged fuel inlet, that might cause leaking problems also. Let’s see what are the reasons and solutions for this problem. 


Ford F-150 check fuel fill inlet warning also means your fuel fill inlet might be damaged. Especially if you drive off-road for a long time. 

With excessive pressure from the off-road track, the fuel fill inlet gets damaged or even the inlet cap might be busted.  


  1. Use the OBD2 scanner to find out if there is more damage to the fuel fill inlet. Look for trouble code P0455 or P0456 to ensure there is damage. 
  2. If the filler neck is broken, you should repair or replace it. It will cost you $200-$300 for repair and $10-$100 for a new cap.

The OBD2 scanners are used for checking engine fault codes and running emission diagnostics. Here’s how to use an OBD2 scanner. 

Step 1: The Diagnostic Link Connector must be located.

Step 2: The OBD2 code reader Or scanner must be connected to the DLC.

Step 3: Enter the Information requested on the scanner screen.

Step 4: Access the scanner menu for OBD codes.

Step 5: Identify and understand the OBD codes.

Step 6: Move on to trouble code diagnosis.

Step 7: Reset the check engine light.

The steps of using this scanner might be confusing to you. If so, watch this visual aid for the steps.

Gas Cap Issues

Gas caps protect your fuel fill inlet system from leaking. So let’s dive into the possible reasons and solutions for this issue. 


There might be several issues regarding the gas tank cap. These reasons are:

  • First of all, the gas cap might be over-tightened. The cap’s materials include silicon and a rubber gasket. This ensures a good seal. When you overtighten it, it can break or even fail. 
  • Secondly, a missing gas cap usually happens after refueling your truck. And also, you might not screw the cap all the way. The cap should make a click sound if it is screwed all the way. 
  • Thirdly, the gas cap might be damaged due to debris or many other reasons. 

Ford’s capless system seal here does more harm than good. Relying only on the flawless seal of the fuel door, the capless seal system diverts harmful things away from the fuel tank.  


  1. Replace the broken or damaged gas cap. It will cost you $10-$100.
  2. Clear the debris off the gas cap and see if it is okay. If not, replace it. 
  3. Check again if you screw the cap all the way. 

Faulty Sensor


A faulty FTP (Fuel Tank Pressure) sensor will show you the check fuel fill inlet sign randomly even if everything is fine. Also, the sensor might not show an error report even with a problem within the fuel fill inlet. 

These sensors work precisely but are also sensitive. And thus, these can fail from time to time and result in poor acceleration, engine stalling, difficulty starting, and poor mileage. 


The only solution for faulty sensors is to fix the problem or replace it. Get professional help for fixing or replacing the sensors. It might cost you around $200-$300.

How to Reset the “Check Fuel Fill Inlet” Error Code On Ford F-150?

Using an OBD2 scanner is the easiest way. This scanner will clear off the check fuel fill inlet code if the problem is solved. If you do not have the scanner there’s another method for clearing the code. 

Step 1: First, battery terminals need to be disconnected. Now, leave the battery like this for a couple of minutes. The battery terminal is under the hood of your Ford F-150. This disconnection will allow the ECU to drain completely. Be careful of any electric shocks while doing this. 

Step 2: Now, when the battery terminal is reconnected a new diagnostic cycle will go on. If the problem regarding the fuel fill inlet is solved, the message will clear off.

Step 3: Now, if this doesn’t work, here is another way. Use a wrench or socket and then disconnect the negative lead(black) first and then the positive(red) lead of the battery. 

Step 4: Again, attach the positive(red) lead before the negative(black) lead when reconnecting the battery. 

The only drawback of this method is that it will clear any unstored data in the car’s computer, including any diagnostic trouble codes (DTCs) that may be useful in diagnosing other issues with the vehicle

Can You Drive Long With Check Fuel Fill Inlet Sign?

Yes, If your engine starts to show the check fuel fill inlet sign, you can drive for a while. But if the sign shows repeatedly, you need to take a look at the fuel fill inlet. If the problem is with the gas cap, then you should not drive. Here’s why,

  1. Leaked gas will evaporate from the fuel tank into the cabin and environment, causing a bad smell, severe EVAP issues, and thus pollution.
  2. Reduced gas mileage will result in more fuel spending.
  3. A bad seal or missing gas cap can lead to dirt contamination on the fuel fill inlet. 

So, while the “check fuel fill inlet” sign on your Ford F-150 is not the most threatening issue, you should check it out before driving long. 


How to Replace Fuel Filler Neck on Ford F-150?

Disconnect the electrical connection to remove the fuel filler neck on Ford F-150. Lift up the truck and store the gasoline in a container. Detach the brackets, screws, and bolts from the system. Then, by moving the clamps, slowly remove the filler neck. Now, replace it with the newer neck and screw everything back. 

How Safe Is A Capless Gas Tank?

Yes, a capless gas tank is safe for your car. This feature is available on most new models. While it is easier when refueling, you need to take note of one thing. When using a portable fuel can, be careful not to damage the spring-loaded mini-cap that seals the inlet. 

How to Reset The Fuel Gauge on A Ford F-150?

To reset the fuel gauge on a Ford F-150, first, remove it. Under the engine, there is a wire connector for vehicle speed sensors on your Ford F-150. There should be wire connectors on the fuel gauge and instrument cluster. Turn it counterclockwise and that should reset the fuel gauge.    

Final Words

Ford F-150 check fuel fill inlet sign is not the grave of the problems and also not the least. Just be careful and check the gas cap when filling up your F-150 truck with gas. And also, properly clean the fuel fill inlet from time to time.

That should do it. 

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William Baldwin

This Is William Baldwin, The Founder & Managing Editor of this website. Me and my team share automotive tips, tricks, and news

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Talha Atta

Talha Atta, a Mechanical Engineer and experienced technical content writer and editor at with a passion for the automotive industry.