Advanced Diagnostics

DTC P0400: Exhaust Gas Recirculation (EGR) System Leak Detected (Engine Type: R18A1)




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 engine control module (ECM)/powertrain control module (PCM) detects this as a malfunction (the likely cause is leakage from the external piping), and DTC P0400 is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The A/F sensor response parameter according to the opening and closing of the EGR is 31,457 (LT80A) or more.




Driving Pattern
1. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
2. Drive the vehicle at a steady speed of 25 mph (40 km/h) or less, for at least 5 minutes.
3. Then, drive immediately at a steady speed between 26 - 81 mph (41 - 130 km/h) for at least 8.5 seconds.

- If the EVAP monitor runs instead of the HO2S monitor, turn the engine off, then restart it, and the HO2S monitor will restart.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the ECM/PCM memory. If the malfunction recurs during the next (second) drive cycle, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.