The exhaust recirculation valve (EGR) on the 1990-2007 Honda Accord V6 may fail, causing:
The EGR valve has open and closed positions, and opens or closes on command from the computer.
Exhaust gases constantly pass through the valve when it is open, leaving carbon deposits on the valve. These carbon deposits may lead the the valve sticking in the open or closed position.
To correct this issue, sometimes it is sufficient to clean the valve, but replacement is recommended in all cases.
For further information on your vehicle's issue, try out our diagnostics tool here.