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DTC P0404: EGR Circuit Range/Performance Problem

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  2. Clear the DTC with the HDS.
  3. Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
  4. Do the EGR TEST in the INSPECTION MENU with the HDS.

    Is the result OK? 

    YES  - Intermittent failure, the system is OK at this time. Clean any carbon build-up on the EGR valve with throttle plate cleaner.

    NO  - Go to step 5.

  5. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  6. Disconnect the EGR valve 5P connector.
  7. At the EGR valve side, measure the resistance between EGR valve 5P connector terminals No. 2 and No. 3.
    Fig 1: Measuring Resistance Between EGR Valve 5P Connector Terminals No. 2 And No. 3
    G08069848Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 100 kΩ or more? 

    YES  - Go to step  25.

    NO  - Go to step 8.

  8. At the EGR valve side, measure the resistance between EGR valve 5P connector terminals No. 2 and No. 4.
    Fig 2: Measuring Resistance Between EGR Valve 5P Connector Terminals No. 2 And No. 4
    G08069849Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 100 kΩ or more? 

    YES  - Go to step  25.

    NO  - Go to step 9.

  9. Check for continuity between EGR valve 5P connector terminal No. 5 and body ground.
    Fig 3: Checking Continuity Between EGR Valve 5P Connector Terminal No. 5 And Body Ground
    G08069850Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 10.

    NO  - Repair open in the wire between the EGR valve and G101; M/T (see CONNECTOR TO FUSE/RELAY BOX INDEX ), A/T (see CONNECTOR TO FUSE/RELAY BOX INDEX ), then go to step  26.

  10. Jump the SCS line with the HDS.
  11. Disconnect ECM/PCM connector C (49P).
  12. Check for continuity between ECM/PCM connector terminal C10 and body ground.
    Fig 4: Checking Continuity Between ECM/PCM Connector Terminal C10 And Body Ground
    G08069851Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Repair short in the wire between the ECM/PCM (C10) and the EGR valve, then go to step  26.

    NO  - Go to step 13.

  13. Check for continuity between ECM/PCM connector terminal C10 and EGR valve 5P connector terminal No. 1.
    Fig 5: Checking Continuity Between ECM/PCM Connector Terminal C10 And EGR Valve 5P Connector
    G08069852Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 14.

    NO  - Repair open in the wire between the ECM/PCM (C10) and the EGR valve, then go to step  26.

  14. Remove the EGR valve (see EGR VALVE REPLACEMENT  ).
  15. Clean any carbon build-up on the EGR valve with throttle plate cleaner.
  16. Install the EGR valve (see EGR VALVE REPLACEMENT  ).
  17. Reconnect the EGR valve 5P connector.
  18. Reconnect ECM/PCM connector C (49P).
  19. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  20. Reset the ECM/PCM with the HDS.
  21. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  22. Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
  23. Do the EGR TEST in the INSPECTION MENU with the HDS.

    Is the result OK? 

    YES  - Go to step  32.

    NO  - Go to step 24.

  24. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  25. Replace the EGR valve (see EGR VALVE REPLACEMENT  ).
  26. Reconnect all connectors.
  27. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  28. Reset the ECM/PCM with the HDS.
  29. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  30. Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
  31. Do the EGR TEST in the INSPECTION MENU with the HDS.
  32. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P0404 indicated? 

    YES  - Check for poor connections or loose terminals at the EGR valve and the ECM/PCM, then go to step  1. If the connections and terminals are OK, go to step 33.

    NO  - Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC'S TROUBLESHOOTING .

  33. Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
  34. Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
  35. Do the EGR TEST in the INSPECTION MENU with the HDS.
  36. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P0404 indicated? 

    YES  - Check for poor connections or loose terminals at the EGR valve and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step  34. If the ECM/PCM was substituted, go to step  1.

    NO  - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC'S TROUBLESHOOTING .

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