How to fix error code P0401 on Honda Passport 2001?

EGR System, insufficient flow detected, maybe bad sensor? Your sensor is more than likely fine. It is probably the air intake to the EGR located in the throttle body. Take off the air intake cover and it is right behind the throttle plate. Just clean out the import to the EGR, because it gets clogged up and then the EGR isn't receiving the correct amount of air. Try that before you go spend the money on a pricey sensor.