DTC P0401: EGR System Insufficient Flow

Reset the PCM (see HOW TO RESET THE PCM ).
Test-drive under these conditions:
- Without any electrical load.
- Decelerate from 55 mph (88 km/h) for at least 5 seconds.
Check for a Temporary DTC with the scan tool or the HDS.
Is Temporary DTC P0401 indicated?
1. YES: Clean the intake manifold EGR port with carburetor cleaner. Clean the passage inside the EGR valve with carburetor 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 The Battery Positive Terminal To EGR Valve 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 EGR valve connector terminal No. 6.
Does 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 caburetor cleaner. Clean the passage inside the EGR valve with carburetor cleaner, or replace the EGR valve.