Mitsubishi P0401 Code: Causes, Symptoms, and How To Fix It

Mitsubishi P0401 Code is an emissions-related issue that can cause a variety of problems in your vehicle.

It is most commonly caused by an inefficient exhaust system, but it can also be caused by clogged catalytic converters or worn Mass Air Flow (MAF) sensors.

Key Takeaway

• The P0401 code in Mitsubishi cars indicates a problem with the Exhaust Gas Recirculation (EGR) system, specifically that the EGR flow is insufficient or lower than expected.
• The P0401 code in Mitsubishi cars is typically caused by a blockage, malfunction, or damage in the Exhaust Gas Recirculation (EGR) system, which can be due to a clogged EGR valve, faulty EGR solenoid or pressure sensor, or damaged vacuum lines or wiring.
• Fixing the P0401 code in a Mitsubishi car generally involves cleaning or replacing the EGR valve, fixing or replacing any damaged components like the EGR solenoid or pressure sensor, and repairing or replacing any faulty vacuum lines or wiring.

What Does The P0401 Code Means In Mitsubishi Cars

The P0401 code in Mitsubishi cars indicates that the Exhaust Gas Recirculation (EGR) flow is insufficient.

This typically means that there are not enough exhaust gases passing through the EGR valve, which is an important component for reducing the vehicle’s emissions.

The malfunction could be caused by a clogged EGR valve or EGR tube. If cleaning the EGR valve doesn’t resolve the issue, it may be necessary to check whether the valve itself is functioning properly or if there are issues with other related components such as vacuum lines, solenoids, or wiring.

What Causes P0401 Code In Mitsubishi

• A clogged EGR valve or EGR tube: These components play a crucial role in controlling the flow of exhaust gases. If they become clogged, it can lead to insufficient EGR flow, triggering the P0401 code.
• Failed EGR valve: If the EGR valve itself is malfunctioning or broken, it can cause the P0401 code to appear.
• EGR solenoid faulty: The EGR solenoid controls the flow of vacuum pressure to the EGR valve. If it’s faulty, it can lead to insufficient EGR flow.
• Blocked passage on the EGR system: If there’s a blockage in the EGR system, it can restrict the flow of gases, causing the P0401 code.
• Failed EGR pressure sensor: This sensor monitors the pressure in the EGR system. If it fails, it can result in the P0401 code appearing.

Symptoms of P0401 Code in Mitsubishi

• Decrease in engine performance: The engine might not run as smoothly or efficiently as usual.
• Increase in fuel consumption: Due to the malfunctioning EGR system, the engine may use more fuel than necessary.
• Rough idle: The engine may run unevenly or “stumble” when the vehicle is idling.
• Check Engine Light: The most common symptom is the illumination of the check engine light on the dashboard.
• Engine hesitation: The vehicle might hesitate or stutter when accelerating.
• Unusual smells: There might be an unusual smell due to the increased emissions.

How To Fix P0401 Code In Mitsubishi

• Scan the vehicle to confirm the P0401 code is present
• Inspect the EGR valve
• Check the EGR solenoid and pressure sensor
• Inspect the vacuum lines and wiring
• Rescan the vehicle

Step 1: Scan and Document the Codes

First, use an OBD-II scanner to confirm that the P0401 code is present. Document the freeze frame information for future reference and clear the codes to see if they return.

Step 2: Inspect the EGR Valve

Check the EGR valve for clogs or blockages. If the valve is clogged, clean it using a suitable cleaner. Also, check for any signs of damage.

Step 3: Check the EGR Solenoid and Pressure Sensor

Examine the EGR solenoid and pressure sensor for any signs of malfunction or damage. If these components are faulty, they will need to be replaced.

Step 4: Inspect the Vacuum Lines and Wiring

Check the vacuum lines leading to the EGR valve for any leaks or damages. Also, inspect the wiring and connectors associated with the EGR system. Fix any issues you find.

Step 5: Test the System

After conducting all necessary repairs, clear the codes again and test drive the vehicle to see if the codes return. If the P0401 code does not return, the issue has been resolved.

FAQs

Q: How does a clogged EGR valve lead to the P0401 code?

A: When the EGR valve becomes clogged or dirty, it restricts the flow of exhaust gas to the intake manifold. This leads to a decrease in the amount of recirculated exhaust gas, causing the P0401 code to be triggered.

Q: How do I diagnose the cause of a P0401 code in my Mitsubishi?

A: To diagnose the cause of a P0401 code in your Mitsubishi, you can start by inspecting the EGR valve for any signs of clogging or carbon buildup. You can also use a scan tool to check for any related trouble codes in the vehicle’s computer.

Q: Can I drive my Mitsubishi with a P0401 code?

A: It is generally not recommended to drive your Mitsubishi with a P0401 code for an extended period of time. While the vehicle may still be drivable, the reduced engine performance and potential for further damage to the EGR system should be addressed as soon as possible.

Q: How do I fix a P0401 code in my Mitsubishi?

A: The specific steps to fix a P0401 code in a Mitsubishi can vary depending on the exact cause of the code. However, common solutions include cleaning or replacing the EGR valve, checking and repairing any vacuum leaks in the EGR system, and clearing any carbon buildup in the EGR passages.

Q: Can I fix the P0401 code in my Mitsubishi myself?

A: If you have some mechanical knowledge and experience, you may be able to fix the P0401 code in your Mitsubishi yourself. However, it is recommended to consult the vehicle’s service manual or seek professional assistance to ensure the proper diagnosis and repair of the issue.

Q: How much does it cost to fix a P0401 code in a Mitsubishi?

A: The cost to fix a P0401 code in a Mitsubishi can vary depending on the specific repairs needed and labor costs in your area. As a rough estimate, you can expect to spend between $100 and $500 for parts and labor.

Q: Can a P0401 code cause my Mitsubishi to fail an emissions test?

A: Yes, a P0401 code can cause your Mitsubishi to fail an emissions test. The existence of this code indicates that your vehicle’s exhaust gas recirculation system is not functioning correctly, which can lead to increased emissions.

In Conclusion

Mitsubishi P0401 is a common diagnostic trouble code (DTC) indicating an issue with the exhaust gas recirculation (EGR) system.

This particular code can cause a number of issues in the vehicle, including lower engine power, poor fuel economy, and increased emissions.

Fortunately, this code can often be resolved relatively easily using common tools and techniques.

If the code persists, however, it is best to consult a qualified mechanic, as more serious repair may be necessary.