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DTC P0404: EGR Circuit Range/Performance Problem

WARNING: This page is about a different car, the 2011 Acura TL, 2010 Acura TL, and 2009 Acura TL. 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. 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
    G05990482Courtesy 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
    G05990483Courtesy 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
    G05990484Courtesy 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, then go to step  26

  10. Jump the SCS line with the HDS
  11. Disconnect PCM connector C (49P)
  12. Check for continuity between PCM connector terminal C10 and body ground
    Fig 4: Checking Continuity Between PCM Connector Terminal C10 And Body Ground
    G05990485Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

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

    NO  -Go to step 13

  13. Check for continuity between PCM connector terminal C10 and EGR valve 5P connector terminal No 1
    Fig 5: Checking Continuity Between PCM Connector Terminal C10 And EGR Valve 5P Connector Terminal No 1
    G05990486Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 14

    NO  -Repair open in the wire between the 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 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 PCM with the HDS
  21. Do the PCM idle learn procedure (see 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 PCM with the HDS
  29. Do the PCM idle learn procedure (see 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 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 PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good PCM (see SUBSTITUTING THE ECM/PCM )
  34. 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
  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 PCM If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE ECM/PCM ), then go to step  34 If the PCM was substituted, go to step  1

    NO  -If the PCM was updated, troubleshooting is complete If the PCM was substituted, replace the original 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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