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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 757 (EGR SYSTEM)DTC TROUBLESHOOTINGDTC P0400: EGR SYSTEM LEAK DETECTED
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

DTC P0400: EGR System Leak Detected

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION DTC P0400: EGR System Leak Detected
WARNING: This page is about a different car, the 2011 Honda Insight and 2010 Honda Insight. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Check for a loose or damaged EGR pipe.

    Is the EGR pipe OK? 

    YES  -Go to step 2.

    NO  -Reconnect or replace the EGR pipe, then go to step  7.

  2. Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
  3. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 158°F(70°C)
    • Transmission in D
    • Drive the vehicle at 25 mph (40 km/h) or less for 5 minutes
    • Drive at a steady speed of 25 mph (41 km/h) or more (engine speed between 1,500-3,000 rpm) for 9 seconds or more.
  4. Monitor the OBD STATUS for DTC P0400 in the DTCs MENU with the HDS.

    Does the screen indicate FAILED? 

    YES  -Go to step 5.

    NO  -If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for an exhaust gas leak between the EGR pipe and the EGR valve. If the screen indicates NOT COMPLETED, go to step  3 and recheck.

  5. Turn the ignition switch to LOCK (0).
  6. Replace the EGR valve (see EGR VALVE REPLACEMENT  ).
  7. Turn the ignition switch to ON (II).
  8. Reset the PCM with the HDS.
  9. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  10. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 158°F(70°C)
    • Transmission in D
    • Drive the vehicle at 25 mph (40 km/h) or less for 5 minutes
    • Drive at a steady speed of 25 mph (41 km/h) or more (engine speed between 1,500-3,000 rpm) for 9 seconds or more.
  11. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P0400 indicated? 

    YES  -Check for a leak between the EGR pipe and EGR valve, then go to step  1.

    NO  -Go to step 12.

  12. Monitor the OBD STATUS for DTC P0400 in the DTCs MENU with the HDS.

    Does the screen indicate PASSED? 

    YES  -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 11, go to the indicated DTC's troubleshooting.

    NO  -If the screen indicates FAILED, check for a leak between the EGR pipe and EGR valve, then go to step  1. If the screen indicates NOT COMPLETED, go to step  10.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.