DTC P0400: Exhaust Gas Recirculation (EGR) System Leak Detected: General Description

The exhaust gas recirculation (EGR) deterioration failure conditions include a sticking lift sensor, restricted passages, and leakage from the external piping. At any specific EGR lift value there is a corresponding A/F compensation value. If the A/F compensation value is greater than the corresponding EGR lift value, the powertrain control module (PCM) detects this as a malfunction (the likely cause is leakage from the external piping), and DTC P0400 is stored.