Exhaust Gas Recirculation: Description and Operation

EGR System Schematic:

DESCRIPTION
This system recirculates a small amount of exhaust gas into the intake manifold to reduce the combustion temperature and reduce the NOx emissions. This system consists of the Exhaust Gas Recirculation (EGR) valve, EGR vacuum regulator solenoid, differential pressure feedback EGR sensor, Powertrain Control Module (PCM) and input devices.

DIFFERENTIAL PRESSURE FEEDBACK EGR SENSOR
^ If the differential pressure feedback EGR sensor or circuit has an open or short, Diagnostic Trouble Code No. P0400, P0401, P0402, P1400, P1401 or P1408 is output.
^ If exhaust manifold side or intake manifold side hose is off or plugged, DTC No. P1405 or P1406 is output.

EGR VACUUM REGULATOR SOLENOID
^ If the EGR vacuum regulator solenoid or circuit has an open or short, Diagnostic Trouble Code No. P1409 is output.
^ If the circuit is open, no driveability symptom will be noticed.
^ If the circuit is shorted, the EGR valve will remain open, causing engine stalling and hard starting.