P0400 MAZDA Exhaust Gas Recirculation Flow Malfunction

Possible causes – Exhaust Gas Recirculation (EGR) volume control valve stuck closed– Faulty Exhaust Gas Recirculation (EGR) volume control solenoid valve– Faulty EGR Valve– Faulty EGR temperature sensor and circuit– Exhaust Gas Recirculation (EGR) solenoid valve harness is open or shorted– Exhaust Gas Recirculation (EGR) solenoid valve circuit poor electrical connection– Dead (Weak) battery Tech…