P0400 Exhaust Gas Recirculation Flow Malfunction

Home » OBD Codes » P0400-P0499 » P0400 Exhaust Gas Recirculation Flow Malfunction

P0400 Exhaust Gas Recirculation Flow Malfunction

OBD-II Trouble Code Technical Description

Exhaust Gas Recirculation (EGR) Flow Malfunction

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.

The exhaust gas recirculation (EGR) valve is vacuum controlled valve that regulates the amount of exhaust gases that re-enter the cylinders.

The powertrain control module (PCM) determines how much based on engine load, temp, and other conditions. If the PCM detects that the amount of exhaust gases entering the cylinder were insufficient or non-existent, this code is set.

Symptoms

No symptoms will likely be noticed by the driver other than the MIL (malfunction indicator lamp). However, non visible symptoms will be increased combustion temperature and increased Nox emissions.

Causes

A code P0400 may mean that one or more of the following has happened:

  • Plugged EGR passage which restricts the flow of exhaust gasses
  • Faulty EGR solenoid
  • Faulty EGR solenoid wiring/harness
  • Vacuum lines damaged/disconnected to the EGR valve solenoid or to the EGR valve
  • Faulty EGR valve

    • Possible Solutions

    Since EGR valve designs are different, no one test will suffice:

  • Using a scan tool, operate the EGR valve with the engine running. If the engine stumbles, the problem was likely intermittent wiring problem or intermittent blockage problem
  • If engine doesn’t stumble, operate the EGR valve manually, if possible. If engine doesn’t stumble and die, the ports are likely plugged. Removal of valve and cleaning of all ports will be required
  • Checking of solenoid can only usually be done with a scan tool, because most solenoids operate with a duty cycle of voltage, rather than constant voltage
  • Check all vacuum lines, hoses, etc for any damage
  • Visually inspect the solenoid harness and the solenoid for damage
  • Replace EGR valve

    • Related EGR codes: P0401, 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 p0400 and to solve the problems.

    Make an appointment for diagnosis

    "Delete Error Code Permanently, Disable DTC Error Code Function for p0400 in the ECU"

    In extreme cases, we even have the option to permanently remove the specific DTC p0400 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 p0400.

    Make an appointment for permanent removal of p0400

    CONTACT
    YouTube
    Facebook