Ford P0640 OBD-II Trouble Code Definition: P0640 Manifold Intake Air Heater P0640 Ford OBD-II Trouble CodeDescription: OBD Trouble Code P0640 Intake Air Heater Control Circuit What does the code mean? OBD-ii Code P0640 definition: The intake air (IA) heater is located in the air inlet tube and is used to warm the incoming air to aid […]