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Home >> Acura >> 2001 >> 3.2CL Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 25 (Engine Performance System Self-Diagnostics) >> Diagnostic Tests >> DTC P0401: EGR System Insufficient Flow Detected
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DTC P0401: EGR System Insufficient Flow Detected

WARNING: This page is about a different car, the 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: When substituting or replacement of PCM is recommended, see PCM REMOVAL & REPLACEMENT  for important precautions.
  1. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  2. Start engine. Hold at 3000 RPM with no load (A/T in Park or Neutral) until radiator fan comes on, then let it idle.
  3. Using Honda PGM Tester or the HDS, do the EGR TEST in the INSPECTION menu. If the EGR system is OK, go to next step. If the EGR system is not OK, go to step  6 .
  4. Test drive under the following conditions:
    • Engine coolant temperature more than 158°F (70°C).
    • A/T in "D" position.
    • Vehicle speed at 30 MPH or more and engine speed between 1100 and 2300 RPM.
    • During drive, decelerate (with throttle fully closed) for 5 seconds.
  5. Using the Honda PGM Tester or the HDS, monitor OBD STATUS for DTC P0401 in the DTCs menu. If it is PASSED, problem is intermittent system is OK at this time. If it FAILED, remove EGR valve and EGR plate. Clean the intake manifold EGR port with carburetor cleaner. Also clean the passage inside EGR valve with carburetor cleaner. Install EGR valve and EGR plate. Go to step  8 . If it is EXECUTING, continue driving condition until a result comes in. If it is OUT OF CONDITION , go to step  4 and recheck.
  6. Turn ignition off.
  7. Replace EGR valve.
  8. Turn ignition on.
  9. Turn ignition on. With the Honda PGM tester or the HDS, do PCM RESET in the CLEAR menu. Do the PCM idle learn procedure. See PCM IDLE LEARN PROCEDURE  . Go to next step.
  10. Test drive under the following conditions:
    • Engine coolant temperature more than 158°F (70°C).
    • A/T in "D" position.
    • Vehicle speed at 30 MPH or more and engine speed between 1100 and 2300 RPM.
    • During drive, decelerate (with throttle fully closed) for 5 seconds.
  11. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0401 is set, check for poor connections or loose terminals at EGR valve and PCM connectors. Go to step  1 . If any other Temporary DTCs or DTCs are set, troubleshoot those indicated. If DTC P0401 is not set, go to next step.
  12. Using the Honda PGM Tester or the HDS, monitor OBD STATUS for DTC P0401 in the DTCs menu. If it is PASSED, troubleshooting is done. If it is FAILED, go to step  1 and recheck. If it is EXECUTING, continue driving condition until a result comes in. If it is OUT OF CONDITION , go to step  10 and recheck.
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