P0420 Ford F150 | Meaning, Causes And Solution

The Ford F150 pickup truck is a great choice for people all over the world for its reliability and amazing performance. But even with all its positives, you can still face some serious issues such as the DTC P0420 code on your Ford F150. So, if your Ford is on this DTC code you can diagnose your vehicle by following this article.

The Diagnostic Trouble Code (DTC) P0420 Ford F150 means Catalyst System Efficiency Below Threshold Bank 1. This code indicates an issue within the catalytic converter. The catalytic converter is used to break down pollutant gasses created from the engine to less harmful ones. 

When the Engine Control Module (ECM) detects any problem in the catalytic converter, it sets this DTC code. In this article, we are going to help you identify, diagnose and prevent the problems regarding this DTC code. 

What Does The Code P0420 Mean on Ford F150?

The catalytic converter located in the bank 1 of the catalyst system has two oxygen sensors on each side of the catalytic converter. These sensors tell the system how much pollutants are in the gas and how much the system should break down the pollutants. So, when one of the sensors is not working properly they both show the same readings. This is when the ECM sets the DTC P0420 and turns on the Check Engine Light.

  • P = Powertrain (includes engines, transmission and drivetrain accessories) this is what powers the vehicle.
  • 0 = Generic issue reserved by SAE.
  • 4 = The sub-system connected to the issue. In this case the emission control.
  • 20 = This indicates the particular problem. Which is for this case low efficiency of the catalyst system.

Common Symptoms Of A P0420 on Ford F150

It is necessary to know the symptoms of a problem in order to identify that. If you do not know the symptoms then the problems can be even worse. So, now we are going to learn some common symptoms about the DTC P0420 code on your Ford.

Check Engine Light Illuminated 

The first and the most obvious one. If the check engine light of your ford is illuminated then it surely indicates that the OBD-II vehicle of yours is under a DTC code. So don’t waste time and take immediate action if you see the check engine light is on.

Power Lacking From The Engine

If the engine does not get enough fuel or air flow in it, then you may find the vehicle not providing enough power. Especially on the uphills where the initial power from the throttle is needed. It can often happen if your Ford is on the code P0420.

Speed Not Exceeding 50-70 kmph

It can often happen if the fuel or ignition system does not work properly. The low transmission fluid level can also cause this symptom. So, if you feel like your Ford is not exceeding a certain speed limit on highways, it can be a symptom to the code P0420.

Rotten Egg or Sulfur Smell From The Exhaust Pipe

If somehow gasoline gets into the catalytic converter, it transforms the hydrogen sulfide particles into sulfur dioxide. Which causes the exhaust to smell like rotten eggs. If the vehicle is on the trouble code P0420, it can cause this kind of smell coming out of the exhaust.

What Are Some Potential Causes of A P0420 on Ford F150

Till now we have learned the symptoms of the code P0420. But it is very essential for you to know the causes or reasons of the problem in your pickup. Diagnosing the actual causes can make the task a lot easier. So, now we will know some potential causes of the code P0420 on your Ford F150.

  • Leaked muffler.
  • Leaked exhaust manifold.
  • Damaged catalytic converter.
  • Damaged oxygen sensor.
  • Leaked fuel injector.

How To Diagnose And Fix P0420 Ford F150 Code

Now that you are aware of the causes of the code P0420. We are going to cover every aspect on how to diagnose the causes in this section . So, let’s know everything in details of the diagnosing process.

Repair Leaked Muffler

Muffler is a part of the exhaust which is also called a silencer, a device that helps reduce the noise of the gasses that comes from the engine combustion chamber. A leak in the muffler can cause the gasses to leave the exhaust system before reaching the tail-pipe. If you find a leak in the muffler, it needs to be sealed.

  1. Find the leak by moving your hand around the exhaust system, you will feel air leaking in your hand. However, do not touch the hot exhaust system.
  2. If the leak is small you can apply an epoxy bond. Stir the epoxy and apply it to the leak hole and then dry it out before starting the engine.
  3. If the hole is not small enough to apply epoxy, then wrapping it with an exhaust tape can be a perfect solution.
  4. Using an exhaust clamp can also be a good option if you are not feeling safe with the wrapping. Seal the clamp around the hole and tighten the bolts.
  5. Using an aluminum patch can be effective on holes of any size. Cut the patch by measuring the hole and then wrap it around the leak.

Repairing the leaked muffler can be very cheap if the hole is smaller. A larger hole might need welding in any workshop for which you need to pay labor cost.

Replace Leaked Exhaust Manifold

An exhaust manifold leak can cause the gasses to escape before turning them into less harmful ones. If this happens you might get some strange smells from the exhaust and you might also feel a lack of power from the engine. A leaked exhaust manifold needs replacing right away.

  1. Detach the negative battery cables.
  2. Remove the engine cover by unscrewing the bolts with a wrench.
  3. Find the manifold and spray penetrating oil on the bolts of the manifold.
  4. Remove the bolts using a wrench except one on the cylinder head.
  5. Remove the old manifold and put the new one in place. Put the bolts in their place and tighten them until everything is back in place.
  6. Connect the negative battery cables and see if everything is working properly.

A new exhaust manifold for your Ford F150 can cost you between $800-$850. 

Replace Damaged Catalytic Converter

The catalytic converter converts the pollutant gasses and makes them less harmful while coming out of the exhaust. So, a damaged catalytic converter can cause black smoke out of the exhaust, decrease the engine performance and can make excessive heat on the engine and needs replacement.

  1. Locate the cylinder shaped catalytic converter on the exhaust system. You should find it on the rear end of the exhaust pipe.
  2. Remove the oxygen sensor from the catalytic converter. 
  3. Apply penetrating oil on the bolts of the converter and remove both the front and rear side bolts.
  4. Remove the old catalytic converter and put the new one in place.
  5. Put all the bolts back in place and tighten them properly. 
  6. Put the oxygen sensor back in the converter. Check if everything is working and there is no mistake.
  7. Turn on the engine and move your hands around the converter and see if there is any leak on it.

The average cost to get a new catalytic converter for the Ford F150 is around $1300.

Replace The Damaged Oxygen Sensor

The oxygen sensor measures the amount of unburned oxygen in the exhaust system. It helps the engine to maintain its fuel-air ratio. A damaged Oxygen sensor can make the engine lose power and can make irregular noises. So, a damaged oxygen sensor needs to be replaced right away.

  1. Locate the first oxygen sensor under the hood, it will be right beside the motor on the engine compartment.
  2. Remove the electrical connection on the sensor which is plugged into the exhaust line.
  3. Locate the second sensor on the exhaust pipe on the rear end and remove electrical connection from that one too.
  4. Remove the sensors from their place by using a wrench. Unscrew the bolts holding place and remove them one by one.
  5. Put new sensors in their place and tighten the bolts again. Put the electrical connections back and start the car to check if everything is alright.

An oxygen sensor for your ford is priced between $40-$50. If you need to change both of the sensors then the cost would be $80-$100.

Replace Damaged Fuel Injector

Fuel injectors spray fuels on the engine as mist through a tiny nozzle. They are located in the manifold and help the engine to combust the fuels easily. A clogged fuel injector can be sent to repair shops to clean. But if the injectors are somehow broken or leaked, they need replacement.

  1. Open the hood and remove the engine cover by using a wrench.
  2. Disconnect the electrical wirings on every injectors.
  3. Open the engine manifold by taking off the fuel rail. The injectors will come with it.
  4. Examine the injectors and see which one is broken or damaged. 
  5. Unclip any staple on the damaged injector. Now use your hand wearing a glove and pull the injector off from the fuel rail.
  6. Put a new injector in its place and put the rail back on the manifold. 
  7. Reconnect the electrical wiring and start the engine to see if anything is having an issue.

Replacing only one fuel injector can cost you between $150-$300.

How To Prevent A P0420 Ford F150 Issue From Happening In The Future

Fixing the issue once does not assure you that it won’t happen again. So, now we are going to give some basic instructions on how you can prevent the code from appearing again on your vehicle.

  • Take the Ford to garages for frequent services
  • Change engine oils and brake fluids regularly.
  • Check for the fuel-air ratio on the engine.
  • Check if the sensors are working properly.
  • Make sure the electrical connections on everything are working properly.
  • Make sure there are no leaks on the exhaust system.


We have come to the very end of this article and now we believe we have been able to give all the correct instructions on how to identify the reasons and causes of the code P0420 on your Ford F150.

This kind of code is not to be left unnoticed. So, make sure you are observing the vehicle properly and taking good care of it. If you face the code on your Ford, following the instructions can diagnose the problem. But don’t proceed to anything if they are not properly needed.

After the diagnosing process be very careful for the code not to appear again on your vehicle. We hope this article came in good help to you and we wish all the best for your future with the Ford F150.

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