What does P0400 OBD trouble code mean and how do you repair it?

P0400 - Exhaust Gas Recirculation Flow Malfunction

Possible causes

- Exhaust Gas Recirculation (EGR) solenoid valve harness is open or shorted

- Exhaust Gas Recirculation (EGR) solenoid valve circuit poor electrical connection

- Exhaust Gas Recirculation (EGR) volume control valve stuck closed

- Faulty Exhaust Gas Recirculation (EGR) volume control solenoid valve

- Dead (Weak) battery

- Faulty EGR temperature sensor and circuit

- Faulty EGR Valve