P0401 Exhaust Gas Recirculation Flow Insufficient Detected

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P0401 Exhaust Gas Recirculation Flow Insufficient Detected

Technical Description

Insufficient Exhaust Gas Recirculation (EGR) Flow

What does that mean?

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.

EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

Symptoms

Causes

A code P0401 most likely means one or more of the following has happened:

  • The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
  • There is a blockage in the EGR (tube), most likely carbon buildup
  • The EGR valve is faulty
  • The EGR valve may not be opening due to a lack of vaccuum

    • Possible Solutions

    In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.

  • Use a vacuum pump and pull the EGR valve open while monitoring engine RPM’s & DPFE voltage. There should be a noticable difference in RPM’s with the EGR open
  • Clean out the EGR valve and/or tubing to remove deposits
  • Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
  • Replace the DPFE sensor (with a good quality / OEM one)
  • Replace the EGR valve

    • Related EGR codes: P0400, P0402, P0403, P0404, P0405, P0406, P0407, P0408, P0409

    Need help?

    Let us fix your problem. You are most welcome our diagnosis experts have in most cases the knowledge and skills to find the cause of the error code p0401 and to solve the problems.

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    "Delete Error Code Permanently, Disable DTC Error Code Function for p0401 in the ECU"

    In extreme cases, we even have the option to permanently remove the specific DTC p0401 and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.

    Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p0401.

    Make an appointment for permanent removal of p0401

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