DTC P0401: EGR Insufficient Flow Detected

Reset the ECM/PCM (see HOW TO RESET THE ECM/PCM ).
Test-drive under the following conditions:
- Without any electrical load.
- Decelerate from 55 MPH (88 km/h) for at least 5 seconds.
Check for a Temporary DTC with the HDS or a scan tool.
1. Is Temporary DTC P0401 indicated?
  1. YES: Clean the intake manifold EGR port with throttle body/intake cleaner. Also, clean the passage inside the EGR valve with throttle body/intake cleaner, or replace the EGR valve.
  2. NO: Intermittent failure, go to step 4.
Turn the ignition switch OFF.
Disconnect the EGR valve 6P connector.
Connect the battery positive terminal to EGR valve connector terminal No. 4.

Fig 1: Connecting Battery Positive Terminal To EGR Valve 6P Connector Terminal No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Start the engine and let it idle, then connect the battery negative terminal to terminal No. 6.
1. Did the engine stall or run rough?
  1. YES: Intermittent failure, system is OK at this time.
  2. NO: Clean the intake manifold EGR port with carburetor cleaner. Also, clean the passage inside the EGR valve with carburetor cleaner, or replace the EGR valve.