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P0401 Code In Ford: Causes, Symptoms, and How To Fix




If you own a Ford vehicle, you may be familiar with the P0401 Code. This code indicates that your vehicle’s exhaust gas recirculation (EGR) system is malfunctioning.

The EGR system helps reduce the amount of nitrogen and other pollutants in your car’s emissions by cycling some of the exhaust back into the engine during idle or low engine speeds.

To ensure your car remains compliant with emissions standards, it is important to understand the causes, symptoms, and solutions for the P0401 Code in Ford vehicles.

In this article, we’ll discuss everything you need to know about P0401 Code in Ford and how to fix it.

Key Takeaway

  • The P0401 code in Ford is a diagnostic trouble code (DTC) that indicates an issue with the Exhaust Gas Recirculation (EGR) system, specifically pointing to insufficient exhaust gas flow detected.
  • The P0401 code in Ford is typically caused by a malfunctioning or blocked Exhaust Gas Recirculation (EGR) valve, clogged EGR passages, or a faulty Differential Pressure Feedback Sensor (DPFE).
  • Symptoms of the P0401 code in Ford may include a lit check engine light, reduced fuel efficiency, engine performance issues like hesitations or rough idle, and in severe cases, the smell of fuel from the exhaust.

What Is The P0401 Code In Ford

P0401 Code In Ford Causes, Symptoms, and How To Fix

The P0401 code in Ford is a diagnostic trouble code (DTC) that signifies there’s an issue with the Exhaust Gas Recirculation (EGR) system, specifically indicating that the EGR flow is insufficient.

This could be triggered by various problems within the vehicle’s EGR system, such as a faulty EGR valve, a blocked EGR passageway, or issues with the Differential Pressure Feedback EGR (DPFE) sensor.

It’s a common issue in many Ford vehicles and can cause the check engine light to illuminate and potential performance problems.

What Causes The P0401 Code In Ford

  • A faulty or clogged Exhaust Gas Recirculation (EGR) valve: The EGR valve helps in reducing the emission of nitrogen oxide by recirculating a portion of an engine’s exhaust gas back to the engine cylinders. If it’s not functioning properly or gets clogged, it might trigger the P0401 code.
  • Low vacuum opening the EGR valve from the EGR control solenoid: The EGR system operates under vacuum control. If the vacuum is insufficient, it may not open the EGR valve correctly, leading to the code.
  • EGR passage clogged: The EGR system routes a portion of exhaust gas into the intake manifold where it cools combustion temperatures. If these passages get clogged, it can lead to the code.
  • Faulty EGR Vacuum Modulator Valve or EGR solenoid valve: These components control the flow of exhaust gases in the EGR system. If they fail, it could cause the P0401 code.
  • EGR solenoid valve harness is open or shorted: Electrical issues with the wiring or harness of the EGR solenoid valve can also trigger this code.
  • Faulty or dirty EGR temperature sensor: The EGR temperature sensor monitors the temperature of the exhaust gases. If it’s faulty or dirty, it might not give accurate readings, leading to the P0401 code.

Symptoms Of P0401 Code In Ford

  • Illumination of the Check Engine Light: This is usually the first and most common symptom that drivers will notice.
  • Decreased performance: The vehicle might experience reduced power, poor acceleration, or problems maintaining speed.
  • Rough idle or stalling: The car might stall or idle roughly when at a stop or during low-speed driving.
  • Increased fuel consumption: There could be a noticeable decrease in fuel efficiency due to the improper recirculation of exhaust gases.
  • Unusual smells: There might be a smell of fuel or exhaust in or around the vehicle due to incorrect exhaust gas recirculation.
  • Engine knocking or pinging sound: This is caused by pre-detonation or ‘pinging’ in the cylinders, which can occur if the EGR system isn’t working properly.

How To Fix P0401 Code In Ford

Here is how to fix the P0401 code in Ford:

Step 1: Record the Code and Clear It

When your diagnostic tool reads a P0401 code, record it along with any other codes. Then, clear the code from your vehicle’s computer to see if it returns. If it does, you know the issue is ongoing and not a one-time error.

Step 2: Inspect the EGR Valve

Check the EGR valve for any signs of damage or clogging. If it’s dirty, try cleaning it with a suitable cleaner. If it’s damaged or heavily clogged, it may need to be replaced.

Step 3: Check the EGR Passages

Examine the passages that lead to the EGR valve. If they’re clogged, clean them out. This often involves removing parts to access the passages, so it might be best left to a professional unless you’re comfortable with vehicle repairs.

Step 4: Examine the Vacuum Hoses and Lines

Inspect the vacuum hoses and lines that control the EGR system. Look for any signs of damage, leaks, or clogs. Replace or clean as necessary.

Step 5: Inspect the DPFE Sensor

The Differential Pressure Feedback EGR (DPFE) sensor monitors the EGR system’s operation. If it’s faulty, it could be causing the P0401 code. Examine it for any signs of damage or malfunction, and replace it if necessary.

Step 6: Reset the Check Engine Light

After making any necessary repairs, use your diagnostic tool to clear the code again. If the repairs were successful, the check engine light should stay off when you start the vehicle.


Q: How does the EGR system work?

A: The EGR system in a Ford is responsible for recirculating a portion of the exhaust gases back into the combustion chambers. This helps to reduce emissions and lower combustion temperatures, improving fuel economy and engine performance.

Q: How can I diagnose the P0401 code in my Ford?

A: To diagnose the P0401 code in your Ford, you can start by inspecting the EGR valve and its associated components for any signs of damage or blockage. You can also use a scan tool to check for any stored trouble codes and to monitor the EGR system parameters.

Q: Can I still drive my Ford with a P0401 code?

A: While it is technically possible to continue driving your Ford with a P0401 code, it is not recommended. The EGR system is an important component for emission control and engine performance. It is best to have the issue diagnosed and repaired to prevent further damage to the engine.

Q: Will a P0401 code cause my Ford to fail emission tests?

A: Yes, a P0401 code can cause your Ford to fail emission tests since it indicates a problem with the EGR system. The EGR system plays a crucial role in reducing emissions, and a malfunction can lead to increased pollution levels.

Q: Can I reset the P0401 code in my Ford without fixing the underlying issue?

A: Yes, you can reset the P0401 code in your Ford by disconnecting the battery or using a scan tool to clear the trouble codes. However, if you haven’t fixed the underlying issue, the code is likely to return, and the problem will persist.

Q: Can a P0401 code in a Ford cause other problems?

A: Yes, a P0401 code in a Ford can potentially cause other problems if left unresolved. The improper functioning of the EGR system can lead to decreased fuel efficiency, reduced power, rough idle, and increased emissions. It is best to address the issue promptly to avoid any further complications.

Q: Can I fix the P0401 code in my Ford by cleaning the EGR valve?

A: In some cases, cleaning the EGR valve can fix the P0401 code in a Ford. If the valve is clogged with carbon deposits, cleaning it thoroughly can restore proper flow and function. However, if the valve is damaged or malfunctioning, it may need to be replaced instead.

In Conclusion

The P0401 code is one of the most common and troublesome codes that can occur in Ford vehicles.

This diagnostic trouble code indicates a problem with the exhaust gas recirculation system (EGR) circuit, often caused by clogged EGR valves, poor vacuum connections, or defective sensors.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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