Ford P0400 OBD-II Trouble Code Definition: P0400 Exhaust Gas Recirculation Flow P0400 Ford OBD-II Trouble CodeDescription: OBD Trouble Code P0400 Exhaust Gas Recirculation Flow What does the code mean? OBD-ii Code P0400 definition: The exhaust gas recirculation (EGR) valve is vacuum controlled valve that regulates the amount of exhaust gases that re-enter the cylinders. The powertrain […]